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    <title>DEV Community: Muhammad Zubair Bin Akbar</title>
    <description>The latest articles on DEV Community by Muhammad Zubair Bin Akbar (@zubairakbar).</description>
    <link>https://dev.to/zubairakbar</link>
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      <title>DEV Community: Muhammad Zubair Bin Akbar</title>
      <link>https://dev.to/zubairakbar</link>
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    <item>
      <title>Why Memory Bandwidth Matters in HPC</title>
      <dc:creator>Muhammad Zubair Bin Akbar</dc:creator>
      <pubDate>Mon, 12 Oct 2026 17:49:12 +0000</pubDate>
      <link>https://dev.to/zubairakbar/why-memory-bandwidth-matters-in-hpc-1f8k</link>
      <guid>https://dev.to/zubairakbar/why-memory-bandwidth-matters-in-hpc-1f8k</guid>
      <description>&lt;p&gt;Imagine having a powerful CPU with dozens of cores, but those cores spend time waiting for data from memory.&lt;/p&gt;

&lt;p&gt;The processor is ready to work, but the data isn't arriving quickly enough.&lt;/p&gt;

&lt;p&gt;This is one reason why adding more CPU cores doesn't always make an HPC application faster.&lt;/p&gt;

&lt;h2&gt;
  
  
  Memory capacity vs. memory bandwidth
&lt;/h2&gt;

&lt;p&gt;These two terms sound similar, but they describe different things.&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;Memory capacity&lt;/strong&gt; is how much data can fit in memory. For example, a node might have 256 GB of RAM.&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;Memory bandwidth&lt;/strong&gt; is how quickly data can move between memory and the processor. It is commonly measured in GB/s.&lt;/p&gt;

&lt;p&gt;Think of memory as a warehouse.&lt;/p&gt;

&lt;p&gt;Capacity tells you how much stock the warehouse can hold. Bandwidth tells you how quickly goods can be delivered to the workers.&lt;/p&gt;

&lt;p&gt;A large warehouse doesn't automatically mean goods can be delivered quickly.&lt;/p&gt;

&lt;p&gt;The same applies to HPC systems.&lt;/p&gt;

&lt;h2&gt;
  
  
  Why does this matter in HPC?
&lt;/h2&gt;

&lt;p&gt;HPC applications process large amounts of data, often across many CPU cores.&lt;/p&gt;

&lt;p&gt;Consider an application that repeatedly reads arrays from memory, performs calculations, and writes the results back.&lt;/p&gt;

&lt;p&gt;If the CPU can process data faster than memory can supply it, the processor may spend time waiting rather than performing useful calculations.&lt;/p&gt;

&lt;p&gt;This is called a &lt;strong&gt;memory bandwidth bottleneck&lt;/strong&gt;.&lt;/p&gt;

&lt;p&gt;Adding more CPU cores might not help much because those cores must share the available memory bandwidth.&lt;/p&gt;

&lt;h2&gt;
  
  
  A simple example
&lt;/h2&gt;

&lt;p&gt;Imagine a compute node with 32 CPU cores.&lt;/p&gt;

&lt;p&gt;Initially, only 8 cores are running an application, and performance is good.&lt;/p&gt;

&lt;p&gt;You increase the workload to 16 cores, then 32 cores.&lt;/p&gt;

&lt;p&gt;However, the application becomes only slightly faster.&lt;/p&gt;

&lt;p&gt;Why?&lt;/p&gt;

&lt;p&gt;The additional cores increase demand for data, but the memory subsystem cannot deliver that data proportionally faster.&lt;/p&gt;

&lt;p&gt;The CPUs are not necessarily too slow. The application may be limited by how quickly data reaches them.&lt;/p&gt;

&lt;p&gt;This is one reason HPC performance doesn't always scale linearly with the number of CPU cores.&lt;/p&gt;

&lt;h2&gt;
  
  
  How can HPC engineers investigate it?
&lt;/h2&gt;

&lt;p&gt;When an application stops scaling as expected, CPU utilization alone doesn't tell the whole story.&lt;/p&gt;

&lt;p&gt;Engineers may investigate:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;
&lt;strong&gt;Memory bandwidth:&lt;/strong&gt; Is the application reaching the memory subsystem's throughput limits?&lt;/li&gt;
&lt;li&gt;
&lt;strong&gt;NUMA placement:&lt;/strong&gt; Are processes accessing memory attached to another CPU socket?&lt;/li&gt;
&lt;li&gt;
&lt;strong&gt;Memory access patterns:&lt;/strong&gt; Is the application accessing data efficiently?&lt;/li&gt;
&lt;li&gt;
&lt;strong&gt;CPU affinity:&lt;/strong&gt; Are processes and threads placed appropriately on the available cores?&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Tools such as &lt;code&gt;numastat&lt;/code&gt;, &lt;code&gt;perf&lt;/code&gt;, and hardware performance counters can help investigate these issues, depending on the system and available permissions.&lt;/p&gt;

&lt;h2&gt;
  
  
  The bigger picture
&lt;/h2&gt;

&lt;p&gt;HPC performance depends on more than processor speed.&lt;/p&gt;

&lt;p&gt;CPU cores need data from memory. Applications may also depend on storage, network communication, and synchronization between processes.&lt;/p&gt;

&lt;p&gt;When one part cannot keep up with the others, it can limit the performance of the entire application.&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;The key takeaway:&lt;/strong&gt; More CPU cores are useful only when the application and the rest of the system can keep them productive.&lt;/p&gt;

&lt;p&gt;In HPC, understanding how quickly data moves can be just as important as understanding how quickly a processor calculates.&lt;/p&gt;

</description>
      <category>memorybandwidth</category>
      <category>cpu</category>
      <category>highperformancecomputing</category>
      <category>networking</category>
    </item>
    <item>
      <title>Why More CPU Cores Don't Always Make an HPC Application Faster</title>
      <dc:creator>Muhammad Zubair Bin Akbar</dc:creator>
      <pubDate>Sun, 04 Oct 2026 15:39:09 +0000</pubDate>
      <link>https://dev.to/zubairakbar/why-more-cpu-cores-dont-always-make-an-hpc-application-faster-2g02</link>
      <guid>https://dev.to/zubairakbar/why-more-cpu-cores-dont-always-make-an-hpc-application-faster-2g02</guid>
      <description>&lt;p&gt;If 1 CPU can run a program, then 8 CPUs should make it much faster.&lt;/p&gt;

&lt;p&gt;Right?&lt;/p&gt;

&lt;p&gt;Not necessarily.&lt;/p&gt;

&lt;p&gt;This is one of the first things that can be surprising when learning HPC.&lt;/p&gt;

&lt;p&gt;We can keep adding CPU cores to a system, but that does not mean an application will keep getting proportionally faster.&lt;/p&gt;

&lt;p&gt;The reason comes down to &lt;strong&gt;parallelism&lt;/strong&gt;.&lt;/p&gt;

&lt;h2&gt;
  
  
  Not every part of a program can run in parallel
&lt;/h2&gt;

&lt;p&gt;Imagine an application that takes 100 seconds to run on one CPU.&lt;/p&gt;

&lt;p&gt;Suppose:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;80 seconds can be parallelised&lt;/li&gt;
&lt;li&gt;20 seconds must run sequentially&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;The 80 second part can use multiple CPU cores.&lt;/p&gt;

&lt;p&gt;But the 20 second part still has to run one step after another.&lt;/p&gt;

&lt;p&gt;So even if we give the application 100 CPU cores, that sequential portion doesn't magically disappear.&lt;/p&gt;

&lt;p&gt;This is the basic idea behind &lt;strong&gt;Amdahl's Law&lt;/strong&gt;.&lt;/p&gt;

&lt;h2&gt;
  
  
  What happens as we add more cores?
&lt;/h2&gt;

&lt;p&gt;Imagine the application running on:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;1 core   → 100 seconds
2 cores  → 60 seconds
4 cores  → 40 seconds
8 cores  → 30 seconds
16 cores → 25 seconds
32 cores → 23 seconds
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;We're adding more and more CPU cores.&lt;/p&gt;

&lt;p&gt;But the improvement gets smaller.&lt;/p&gt;

&lt;p&gt;Why?&lt;/p&gt;

&lt;p&gt;Because eventually the parts of the application that cannot be parallelised become the limiting factor.&lt;/p&gt;

&lt;p&gt;The application has reached a point where adding more CPUs provides very little benefit.&lt;/p&gt;

&lt;h2&gt;
  
  
  The problem isn't always the CPU
&lt;/h2&gt;

&lt;p&gt;This is an important idea in HPC.&lt;/p&gt;

&lt;p&gt;When an application doesn't scale well, the CPU may not be the problem.&lt;/p&gt;

&lt;p&gt;The application might be waiting for:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Memory&lt;/li&gt;
&lt;li&gt;Network communication&lt;/li&gt;
&lt;li&gt;Storage I/O&lt;/li&gt;
&lt;li&gt;Synchronisation between processes&lt;/li&gt;
&lt;li&gt;Locks&lt;/li&gt;
&lt;li&gt;Other processes&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;For example, imagine an MPI application running across many compute nodes.&lt;/p&gt;

&lt;p&gt;Each process may need to exchange data with other processes.&lt;/p&gt;

&lt;p&gt;Adding more nodes gives you more CPUs, but it also means more communication between them.&lt;/p&gt;

&lt;p&gt;At some point, the communication overhead can start becoming significant.&lt;/p&gt;

&lt;p&gt;You have more computing resources, but you are spending more time coordinating them.&lt;/p&gt;

&lt;h2&gt;
  
  
  Strong scaling vs weak scaling
&lt;/h2&gt;

&lt;p&gt;This leads to two important HPC concepts.&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;Strong scaling&lt;/strong&gt; asks:&lt;/p&gt;

&lt;blockquote&gt;
&lt;p&gt;How much faster can I solve the same problem by adding more resources?&lt;/p&gt;
&lt;/blockquote&gt;

&lt;p&gt;For example:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;Same problem
     ↓
8 cores → 16 cores → 32 cores → 64 cores
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;Ideally, the runtime keeps decreasing.&lt;/p&gt;

&lt;p&gt;But eventually the speedup usually becomes smaller.&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;Weak scaling&lt;/strong&gt; asks something different:&lt;/p&gt;

&lt;blockquote&gt;
&lt;p&gt;Can I solve a larger problem by adding more resources while keeping the workload per resource roughly the same?&lt;/p&gt;
&lt;/blockquote&gt;

&lt;p&gt;For example:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;8 cores   → small problem
16 cores  → larger problem
32 cores  → even larger problem
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;Both are important ways of understanding HPC application performance.&lt;/p&gt;

&lt;h2&gt;
  
  
  More cores can even make things worse
&lt;/h2&gt;

&lt;p&gt;This can sound strange, but adding resources can sometimes reduce efficiency.&lt;/p&gt;

&lt;p&gt;Imagine 16 processes constantly exchanging data.&lt;/p&gt;

&lt;p&gt;Now increase that to 128 processes.&lt;/p&gt;

&lt;p&gt;There are many more processes that may need to communicate and synchronise.&lt;/p&gt;

&lt;p&gt;If the application's communication pattern doesn't scale well, the additional resources can create more overhead than useful computation.&lt;/p&gt;

&lt;p&gt;The CPUs aren't necessarily doing more useful work.&lt;/p&gt;

&lt;p&gt;They may be spending more time waiting.&lt;/p&gt;

&lt;h2&gt;
  
  
  This is why benchmarking matters
&lt;/h2&gt;

&lt;p&gt;You cannot determine how well an HPC application will scale simply by looking at the number of CPU cores in a server.&lt;/p&gt;

&lt;p&gt;You need to test it.&lt;/p&gt;

&lt;p&gt;For example:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;1 node   → 100 seconds
2 nodes  → 55 seconds
4 nodes  → 32 seconds
8 nodes  → 25 seconds
16 nodes → 23 seconds
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;The application is scaling.&lt;/p&gt;

&lt;p&gt;But not linearly.&lt;/p&gt;

&lt;p&gt;Doubling the resources does not always halve the runtime.&lt;/p&gt;

&lt;p&gt;That is normal for many real world HPC applications.&lt;/p&gt;

&lt;h2&gt;
  
  
  The goal isn't always maximum CPU usage
&lt;/h2&gt;

&lt;p&gt;Another important lesson is that &lt;strong&gt;100% CPU utilisation doesn't automatically mean an application is scaling well&lt;/strong&gt;.&lt;/p&gt;

&lt;p&gt;An application could be using every CPU core while spending significant time waiting for memory, communicating with other processes or performing synchronisation.&lt;/p&gt;

&lt;p&gt;This is why HPC performance analysis looks at much more than CPU utilisation.&lt;/p&gt;

&lt;p&gt;You may need to investigate:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;CPU utilisation&lt;/li&gt;
&lt;li&gt;Memory bandwidth&lt;/li&gt;
&lt;li&gt;NUMA behaviour&lt;/li&gt;
&lt;li&gt;Network traffic&lt;/li&gt;
&lt;li&gt;MPI communication&lt;/li&gt;
&lt;li&gt;Storage I/O&lt;/li&gt;
&lt;li&gt;Process placement&lt;/li&gt;
&lt;li&gt;CPU affinity&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;The bottleneck can move as you add resources.&lt;/p&gt;

&lt;h2&gt;
  
  
  So how many CPU cores should you use?
&lt;/h2&gt;

&lt;p&gt;There isn't one answer.&lt;/p&gt;

&lt;p&gt;The right number depends on the application.&lt;/p&gt;

&lt;p&gt;For some workloads:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;8 cores → good scaling
16 cores → better
32 cores → better
64 cores → little additional benefit
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;For another application, 64 or 128 cores might still provide excellent scaling.&lt;/p&gt;

&lt;p&gt;This is why HPC systems don't simply try to give every application as many CPUs as possible.&lt;/p&gt;

&lt;p&gt;The goal is to use the resources &lt;strong&gt;efficiently&lt;/strong&gt;.&lt;/p&gt;

&lt;h2&gt;
  
  
  The bigger HPC lesson
&lt;/h2&gt;

&lt;p&gt;HPC isn't simply about having more CPUs.&lt;/p&gt;

&lt;p&gt;It's about using parallel resources effectively.&lt;/p&gt;

&lt;p&gt;A well designed application can divide a large problem across many CPU cores or nodes and achieve significant speedup.&lt;/p&gt;

&lt;p&gt;But parallelism has limits.&lt;/p&gt;

&lt;p&gt;Sequential work, communication, synchronisation, memory bandwidth and I/O can all become bottlenecks.&lt;/p&gt;

&lt;p&gt;So the next time someone says:&lt;/p&gt;

&lt;blockquote&gt;
&lt;p&gt;"This server has twice as many CPU cores, so the application should be twice as fast."&lt;/p&gt;
&lt;/blockquote&gt;

&lt;p&gt;The better question is:&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;"Does the application scale?"&lt;/strong&gt;&lt;/p&gt;

&lt;p&gt;That's one of the fundamental questions in HPC performance.&lt;/p&gt;

&lt;p&gt;And sometimes, the answer is:&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;not as much as you might expect.&lt;/strong&gt;&lt;/p&gt;

</description>
      <category>ai</category>
      <category>cpu</category>
      <category>parallelcomputing</category>
      <category>hpc</category>
    </item>
    <item>
      <title>Why Does HPC Need InfiniBand?</title>
      <dc:creator>Muhammad Zubair Bin Akbar</dc:creator>
      <pubDate>Wed, 30 Sep 2026 18:50:16 +0000</pubDate>
      <link>https://dev.to/zubairakbar/why-does-hpc-need-infiniband-2c9e</link>
      <guid>https://dev.to/zubairakbar/why-does-hpc-need-infiniband-2c9e</guid>
      <description>&lt;p&gt;When people first learn about HPC clusters, they often notice something unusual.&lt;/p&gt;

&lt;p&gt;The compute nodes don't just have Ethernet.&lt;/p&gt;

&lt;p&gt;Many HPC clusters also have &lt;strong&gt;InfiniBand&lt;/strong&gt;.&lt;/p&gt;

&lt;p&gt;So a natural question is:&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;Why?&lt;/strong&gt;&lt;/p&gt;

&lt;p&gt;If Ethernet already connects computers together, why do HPC clusters need another network?&lt;/p&gt;

&lt;p&gt;The answer becomes clearer when you look at what HPC applications actually do.&lt;/p&gt;

&lt;h2&gt;
  
  
  HPC applications communicate a lot
&lt;/h2&gt;

&lt;p&gt;Consider an MPI application running across 32 compute nodes.&lt;/p&gt;

&lt;p&gt;The application may constantly exchange data between those nodes.&lt;/p&gt;

&lt;p&gt;For example:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;Node 1  &amp;lt;----&amp;gt;  Node 2
  ↕              ↕
Node 3  &amp;lt;----&amp;gt;  Node 4
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;The application isn't just sending an occasional file or SSH connection.&lt;/p&gt;

&lt;p&gt;The compute nodes can be communicating continuously while the application is running.&lt;/p&gt;

&lt;p&gt;That makes network performance extremely important.&lt;/p&gt;

&lt;h2&gt;
  
  
  It's not just about bandwidth
&lt;/h2&gt;

&lt;p&gt;A common first thought is:&lt;/p&gt;

&lt;p&gt;"Just give the cluster a faster network."&lt;/p&gt;

&lt;p&gt;But HPC networking is about more than bandwidth.&lt;/p&gt;

&lt;p&gt;Two important factors are:&lt;/p&gt;

&lt;h3&gt;
  
  
  Bandwidth
&lt;/h3&gt;

&lt;p&gt;How much data can be transferred per second.&lt;/p&gt;

&lt;h3&gt;
  
  
  Latency
&lt;/h3&gt;

&lt;p&gt;How long it takes for a message to travel between nodes.&lt;/p&gt;

&lt;p&gt;For many HPC workloads, both matter.&lt;/p&gt;

&lt;p&gt;A network can have high bandwidth but still have latency that isn't ideal for tightly coupled workloads.&lt;/p&gt;

&lt;h2&gt;
  
  
  Where InfiniBand comes in
&lt;/h2&gt;

&lt;p&gt;InfiniBand was designed for high performance communication.&lt;/p&gt;

&lt;p&gt;It provides:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;High bandwidth&lt;/li&gt;
&lt;li&gt;Low latency&lt;/li&gt;
&lt;li&gt;RDMA&lt;/li&gt;
&lt;li&gt;Efficient communication between nodes&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;One particularly important feature is &lt;strong&gt;RDMA&lt;/strong&gt;.&lt;/p&gt;

&lt;p&gt;RDMA allows data to be transferred directly between the memory of different systems with minimal involvement from the CPU and operating system.&lt;/p&gt;

&lt;p&gt;That can reduce overhead during communication.&lt;/p&gt;

&lt;h2&gt;
  
  
  Why does that matter?
&lt;/h2&gt;

&lt;p&gt;Imagine an MPI application running across hundreds of nodes.&lt;/p&gt;

&lt;p&gt;The application might repeatedly exchange relatively small messages between processes.&lt;/p&gt;

&lt;p&gt;If every communication requires significant CPU and operating system involvement, that overhead can become important.&lt;/p&gt;

&lt;p&gt;With technologies such as RDMA, the network can handle communication more efficiently.&lt;/p&gt;

&lt;p&gt;This is one reason high performance networks are so important in HPC.&lt;/p&gt;

&lt;h2&gt;
  
  
  InfiniBand isn't the only option
&lt;/h2&gt;

&lt;p&gt;InfiniBand isn't the only technology used for HPC networking.&lt;/p&gt;

&lt;p&gt;You can also find:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;High speed Ethernet&lt;/li&gt;
&lt;li&gt;RoCE&lt;/li&gt;
&lt;li&gt;Other specialised interconnects&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Modern Ethernet can provide very high performance, and technologies such as &lt;strong&gt;RoCE&lt;/strong&gt; can provide RDMA capabilities over Ethernet.&lt;/p&gt;

&lt;p&gt;So the question isn't simply:&lt;/p&gt;

&lt;p&gt;"InfiniBand or Ethernet?"&lt;/p&gt;

&lt;p&gt;It's really about what the workload and cluster architecture require.&lt;/p&gt;

&lt;h2&gt;
  
  
  The bigger picture
&lt;/h2&gt;

&lt;p&gt;An HPC cluster is a collection of computers working together.&lt;/p&gt;

&lt;p&gt;The CPUs do the computation.&lt;/p&gt;

&lt;p&gt;The memory holds the data being processed.&lt;/p&gt;

&lt;p&gt;The storage provides the data.&lt;/p&gt;

&lt;p&gt;And the network allows the nodes to communicate.&lt;/p&gt;

&lt;p&gt;If the application spends a lot of time waiting for data from another node, having powerful CPUs won't solve the problem.&lt;/p&gt;

&lt;p&gt;The network becomes part of the application's performance.&lt;/p&gt;

&lt;p&gt;That's why HPC networking is such an important part of cluster design.&lt;/p&gt;

&lt;p&gt;And that's also why you'll often hear technologies such as:&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;InfiniBand → RDMA → MPI → UCX&lt;/strong&gt;&lt;/p&gt;

&lt;p&gt;when talking about HPC communication.&lt;/p&gt;

&lt;p&gt;Understanding how these pieces fit together is much more useful than simply knowing that "HPC uses InfiniBand."&lt;/p&gt;

</description>
      <category>ai</category>
      <category>networking</category>
      <category>infiniband</category>
      <category>highperformancecomputing</category>
    </item>
    <item>
      <title>What Actually Happens After You Run sbatch?</title>
      <dc:creator>Muhammad Zubair Bin Akbar</dc:creator>
      <pubDate>Fri, 25 Sep 2026 20:09:44 +0000</pubDate>
      <link>https://dev.to/zubairakbar/what-actually-happens-after-you-run-sbatch-fke</link>
      <guid>https://dev.to/zubairakbar/what-actually-happens-after-you-run-sbatch-fke</guid>
      <description>&lt;p&gt;If you are learning Slurm, you probably start with a few commands:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight console"&gt;&lt;code&gt;&lt;span class="go"&gt;sbatch job.sh
squeue
&lt;/span&gt;&lt;span class="gp"&gt;scancel &amp;lt;jobid&amp;gt;&lt;/span&gt;&lt;span class="w"&gt;
&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;It is easy to think of sbatch as simply "running a job."&lt;/p&gt;

&lt;p&gt;But that is not really what happens.&lt;/p&gt;

&lt;p&gt;When you run:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight shell"&gt;&lt;code&gt;sbatch job.sh

&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;you are submitting a request to Slurm.&lt;/p&gt;

&lt;p&gt;What happens after that is where things get interesting.&lt;/p&gt;

&lt;h2&gt;
  
  
  sbatch submits the job
&lt;/h2&gt;

&lt;p&gt;Suppose we have a simple script:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight shell"&gt;&lt;code&gt;&lt;span class="c"&gt;#!/bin/bash&lt;/span&gt;

&lt;span class="c"&gt;#SBATCH --job-name=zubair-test&lt;/span&gt;
&lt;span class="c"&gt;#SBATCH --cpus-per-task=4&lt;/span&gt;
&lt;span class="c"&gt;#SBATCH --mem=8G&lt;/span&gt;
&lt;span class="c"&gt;#SBATCH --time=01:00:00&lt;/span&gt;

./my_application
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;When we run:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight shell"&gt;&lt;code&gt;sbatch job.sh

&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;Slurm accepts the job request and gives it a job ID.&lt;/p&gt;

&lt;p&gt;For example:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;Submitted batch job 12345

&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;At this point, your application has not necessarily started.&lt;/p&gt;

&lt;p&gt;The job has simply entered Slurm.&lt;/p&gt;

&lt;p&gt;This is one of the most important concepts to understand:&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;Submitting a job is not the same as running a job.&lt;/strong&gt;&lt;/p&gt;

&lt;h2&gt;
  
  
  The job enters the scheduling system
&lt;/h2&gt;

&lt;p&gt;The Slurm controller now knows about your job.&lt;/p&gt;

&lt;p&gt;You can see it with:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight shell"&gt;&lt;code&gt;squeue

&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;You might see:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;JOBID   PARTITION   NAME   USER           ST   TIME
12345   compute     test   zubair-test    PD   0:00
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;The &lt;code&gt;PD&lt;/code&gt; state means &lt;strong&gt;pending&lt;/strong&gt;.&lt;/p&gt;

&lt;p&gt;The job is waiting for an opportunity to run.&lt;/p&gt;

&lt;p&gt;But why does it have to wait?&lt;/p&gt;

&lt;p&gt;Because Slurm has to make a scheduling decision.&lt;/p&gt;

&lt;h2&gt;
  
  
  Slurm looks at the job's request
&lt;/h2&gt;

&lt;p&gt;The scheduler needs to understand what the job is asking for.&lt;/p&gt;

&lt;p&gt;In our example, the job requested:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;4 CPUs&lt;/li&gt;
&lt;li&gt;8 GB memory&lt;/li&gt;
&lt;li&gt;1 hour of runtime&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;But a real HPC job could request much more:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;16 CPUs
128 GB memory
2 GPUs
4 hours
specific partition
specific features
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;Slurm has to determine whether those requirements can be satisfied.&lt;/p&gt;

&lt;p&gt;And this is where simply looking at "free CPUs" can become misleading.&lt;/p&gt;

&lt;p&gt;A cluster might have idle CPUs but still not be able to run your job because of memory, GPU availability, partition limits, reservations, priorities, dependencies or other scheduling rules.&lt;/p&gt;

&lt;h2&gt;
  
  
  The scheduler decides when the job can run
&lt;/h2&gt;

&lt;p&gt;Slurm's scheduler considers the jobs waiting in the system and the resources available on the cluster.&lt;/p&gt;

&lt;p&gt;It is not simply doing this:&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;"There are 4 free CPUs, so run the job."&lt;/strong&gt;&lt;/p&gt;

&lt;p&gt;Instead, it has to consider the overall scheduling configuration and policies.&lt;/p&gt;

&lt;p&gt;For example:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Which partition can run the job?&lt;/li&gt;
&lt;li&gt;Does the job have enough priority?&lt;/li&gt;
&lt;li&gt;Are the requested CPUs available?&lt;/li&gt;
&lt;li&gt;Is enough memory available?&lt;/li&gt;
&lt;li&gt;Does the job require GPUs?&lt;/li&gt;
&lt;li&gt;Are there reservations?&lt;/li&gt;
&lt;li&gt;Are there account or QoS restrictions?&lt;/li&gt;
&lt;li&gt;Are other jobs already using the required resources?&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;This is why understanding Slurm requires more than memorising commands.&lt;/p&gt;

&lt;p&gt;The commands are the interface.&lt;/p&gt;

&lt;p&gt;The scheduler is the system underneath.&lt;/p&gt;

&lt;h2&gt;
  
  
  An allocation is created
&lt;/h2&gt;

&lt;p&gt;Eventually, Slurm determines that the job can run.&lt;/p&gt;

&lt;p&gt;It allocates the requested resources.&lt;/p&gt;

&lt;p&gt;For example:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;Node: compute-05
CPUs: 4
Memory: 8 GB
Time limit: 1 hour
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;The job changes from:&lt;/p&gt;

&lt;p&gt;&lt;code&gt;PD&lt;/code&gt;&lt;/p&gt;

&lt;p&gt;to:&lt;/p&gt;

&lt;p&gt;&lt;code&gt;R&lt;/code&gt;&lt;/p&gt;

&lt;p&gt;where &lt;code&gt;R&lt;/code&gt; means &lt;strong&gt;running&lt;/strong&gt;.&lt;/p&gt;

&lt;p&gt;Now the job has an allocation.&lt;/p&gt;

&lt;p&gt;This is an important distinction:&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;The scheduler decides what resources the job gets.&lt;/strong&gt;&lt;/p&gt;

&lt;p&gt;The application then runs inside that allocation.&lt;/p&gt;

&lt;h2&gt;
  
  
  The job reaches a compute node
&lt;/h2&gt;

&lt;p&gt;The actual application does not normally run on the Slurm controller.&lt;/p&gt;

&lt;p&gt;The controller manages the cluster and scheduling decisions.&lt;/p&gt;

&lt;p&gt;The job is launched on one or more &lt;strong&gt;compute nodes&lt;/strong&gt;.&lt;/p&gt;

&lt;p&gt;For example:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;Slurm Controller
       |
       |
   Scheduler
       |
       |
   Allocation
       |
       |
   compute-05
       |
       |
   Your application
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;Once the job starts on the compute node, a lot more of the HPC stack becomes involved.&lt;/p&gt;

&lt;p&gt;Linux manages the processes.&lt;/p&gt;

&lt;p&gt;The CPU and memory topology affects performance.&lt;/p&gt;

&lt;p&gt;&lt;a href="https://slurm.schedmd.com/cgroups.html" rel="noopener noreferrer"&gt;cgroups&lt;/a&gt; can control resource usage.&lt;/p&gt;

&lt;p&gt;If GPUs are requested, &lt;a href="https://slurm.schedmd.com/gres.html" rel="noopener noreferrer"&gt;Slurm's GRES configuration&lt;/a&gt; and GPU management become relevant.&lt;/p&gt;

&lt;p&gt;If the application communicates across nodes, the network becomes part of the picture.&lt;/p&gt;

&lt;p&gt;And if it reads or writes large amounts of data, the storage system becomes important.&lt;/p&gt;

&lt;h2&gt;
  
  
  This is where HPC gets interesting
&lt;/h2&gt;

&lt;p&gt;Consider an MPI application running across 32 nodes.&lt;/p&gt;

&lt;p&gt;Slurm has already done its job of allocating resources.&lt;/p&gt;

&lt;p&gt;But now the application depends on many other parts of the system working together.&lt;/p&gt;

&lt;p&gt;You might have:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;CPUs and NUMA topology&lt;/li&gt;
&lt;li&gt;memory&lt;/li&gt;
&lt;li&gt;GPUs&lt;/li&gt;
&lt;li&gt;InfiniBand or Ethernet&lt;/li&gt;
&lt;li&gt;RDMA&lt;/li&gt;
&lt;li&gt;MPI&lt;/li&gt;
&lt;li&gt;UCX&lt;/li&gt;
&lt;li&gt;parallel storage&lt;/li&gt;
&lt;li&gt;Linux processes and cgroups&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;So when an HPC application is slow, the problem is not necessarily Slurm.&lt;/p&gt;

&lt;p&gt;Slurm may have allocated the resources correctly.&lt;/p&gt;

&lt;p&gt;The bottleneck could instead be CPU placement, memory access, network communication, storage I/O, GPU utilisation or the application itself.&lt;/p&gt;

&lt;p&gt;That is why HPC administration involves understanding how these layers interact.&lt;/p&gt;

&lt;h2&gt;
  
  
  From one command to an entire system
&lt;/h2&gt;

&lt;p&gt;This is what makes a simple command like:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight shell"&gt;&lt;code&gt;sbatch job.sh

&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;much more interesting than it first appears.&lt;/p&gt;

&lt;p&gt;You submit a job.&lt;/p&gt;

&lt;p&gt;Slurm records the request.&lt;/p&gt;

&lt;p&gt;The scheduler evaluates it.&lt;/p&gt;

&lt;p&gt;Resources are allocated.&lt;/p&gt;

&lt;p&gt;The job is launched on compute nodes.&lt;/p&gt;

&lt;p&gt;Then Linux, CPUs, memory, GPUs, networking, storage and the application all become part of the execution.&lt;/p&gt;

&lt;p&gt;So the next time you run:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight shell"&gt;&lt;code&gt;sbatch job.sh

&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;remember that you are not simply "starting a program."&lt;/p&gt;

&lt;p&gt;You are asking an entire resource management system to find a place for that program to run.&lt;/p&gt;

&lt;p&gt;And understanding that process is one of the foundations of understanding HPC.&lt;/p&gt;

</description>
      <category>ai</category>
      <category>hpc</category>
      <category>slurm</category>
      <category>parallelcomputing</category>
    </item>
    <item>
      <title>Kubernetes and Slurm are both popular for AI and HPC workloads, but they serve different purposes. This article explores their strengths, trade offs, and ideal use cases across scheduling, GPUs, distributed training, networking, and more.</title>
      <dc:creator>Muhammad Zubair Bin Akbar</dc:creator>
      <pubDate>Thu, 16 Jul 2026 11:54:49 +0000</pubDate>
      <link>https://dev.to/zubairakbar/kubernetes-and-slurm-are-both-popular-for-ai-and-hpc-workloads-but-they-serve-different-purposes-3649</link>
      <guid>https://dev.to/zubairakbar/kubernetes-and-slurm-are-both-popular-for-ai-and-hpc-workloads-but-they-serve-different-purposes-3649</guid>
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</description>
      <category>ai</category>
      <category>infrastructure</category>
      <category>kubernetes</category>
      <category>machinelearning</category>
    </item>
    <item>
      <title>Slurm vs Kubernetes: Understanding the Right Tool for the Right Workload</title>
      <dc:creator>Muhammad Zubair Bin Akbar</dc:creator>
      <pubDate>Thu, 16 Jul 2026 11:48:29 +0000</pubDate>
      <link>https://dev.to/zubairakbar/slurm-vs-kubernetes-understanding-the-right-tool-for-the-right-workload-3g9h</link>
      <guid>https://dev.to/zubairakbar/slurm-vs-kubernetes-understanding-the-right-tool-for-the-right-workload-3g9h</guid>
      <description>&lt;h2&gt;
  
  
  Why This Comparison Matters
&lt;/h2&gt;

&lt;p&gt;As AI and High Performance Computing (HPC) continue to converge, one question appears in almost every infrastructure discussion:&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;Should we use Kubernetes or Slurm?&lt;/strong&gt;&lt;/p&gt;

&lt;p&gt;The answer is rarely as simple as choosing one over the other.&lt;/p&gt;

&lt;p&gt;Kubernetes dominates cloud native application deployment, while Slurm has been the scheduler of choice for scientific computing and supercomputers for decades. Today, organizations running AI training, machine learning, simulations, computational chemistry, CFD, and financial modeling often need to decide which platform better fits their workloads.&lt;/p&gt;

&lt;p&gt;This article explains where each platform excels, where it struggles, and when using both together makes the most sense.&lt;/p&gt;




&lt;h2&gt;
  
  
  Understanding Their Different Goals
&lt;/h2&gt;

&lt;p&gt;Although both systems schedule workloads across clusters, they were built with completely different objectives.&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;Kubernetes&lt;/strong&gt; was designed to orchestrate containers and microservices at massive scale.&lt;/p&gt;

&lt;p&gt;Its priorities include:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;High availability&lt;/li&gt;
&lt;li&gt;Auto scaling&lt;/li&gt;
&lt;li&gt;Self healing applications&lt;/li&gt;
&lt;li&gt;Rolling updates&lt;/li&gt;
&lt;li&gt;Service discovery&lt;/li&gt;
&lt;li&gt;Cloud native deployments&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;&lt;strong&gt;Slurm&lt;/strong&gt;, on the other hand, was built specifically for HPC environments where maximizing compute efficiency is the primary objective.&lt;/p&gt;

&lt;p&gt;Its priorities include:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Efficient resource allocation&lt;/li&gt;
&lt;li&gt;Fair scheduling&lt;/li&gt;
&lt;li&gt;Job queuing&lt;/li&gt;
&lt;li&gt;Large MPI jobs&lt;/li&gt;
&lt;li&gt;GPU scheduling&lt;/li&gt;
&lt;li&gt;High cluster utilization&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Both schedule workloads but they optimize for entirely different problems.&lt;/p&gt;




&lt;h2&gt;
  
  
  Architecture Comparison
&lt;/h2&gt;

&lt;div class="table-wrapper-paragraph"&gt;&lt;table&gt;
&lt;thead&gt;
&lt;tr&gt;
&lt;th&gt;Kubernetes&lt;/th&gt;
&lt;th&gt;Slurm&lt;/th&gt;
&lt;/tr&gt;
&lt;/thead&gt;
&lt;tbody&gt;
&lt;tr&gt;
&lt;td&gt;Container orchestrator&lt;/td&gt;
&lt;td&gt;HPC workload manager&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;API driven&lt;/td&gt;
&lt;td&gt;Job scheduler&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;Works with pods&lt;/td&gt;
&lt;td&gt;Works with batch jobs&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;Focuses on services&lt;/td&gt;
&lt;td&gt;Focuses on compute jobs&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;Cloud native&lt;/td&gt;
&lt;td&gt;HPC native&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;Long running applications&lt;/td&gt;
&lt;td&gt;Batch oriented workloads&lt;/td&gt;
&lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;&lt;/div&gt;




&lt;h2&gt;
  
  
  Resource Scheduling
&lt;/h2&gt;

&lt;p&gt;This is where the biggest differences appear.&lt;/p&gt;

&lt;h3&gt;
  
  
  Kubernetes Scheduling
&lt;/h3&gt;

&lt;p&gt;Kubernetes schedules Pods based on:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;CPU requests&lt;/li&gt;
&lt;li&gt;Memory requests&lt;/li&gt;
&lt;li&gt;Labels&lt;/li&gt;
&lt;li&gt;Affinity rules&lt;/li&gt;
&lt;li&gt;Taints and tolerations&lt;/li&gt;
&lt;li&gt;Custom schedulers&lt;/li&gt;
&lt;li&gt;Priority classes&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;It primarily answers:&lt;/p&gt;

&lt;blockquote&gt;
&lt;p&gt;"Where should this container run?"&lt;/p&gt;
&lt;/blockquote&gt;

&lt;p&gt;The scheduler focuses on cluster health rather than maximizing utilization.&lt;/p&gt;




&lt;h3&gt;
  
  
  Slurm Scheduling
&lt;/h3&gt;

&lt;p&gt;Slurm considers far more information.&lt;/p&gt;

&lt;p&gt;Examples include:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Available CPUs&lt;/li&gt;
&lt;li&gt;Memory&lt;/li&gt;
&lt;li&gt;GPUs&lt;/li&gt;
&lt;li&gt;Licenses&lt;/li&gt;
&lt;li&gt;Partitions&lt;/li&gt;
&lt;li&gt;QoS&lt;/li&gt;
&lt;li&gt;Reservations&lt;/li&gt;
&lt;li&gt;Node topology&lt;/li&gt;
&lt;li&gt;NUMA layout&lt;/li&gt;
&lt;li&gt;Job priority&lt;/li&gt;
&lt;li&gt;Fair share&lt;/li&gt;
&lt;li&gt;Backfill opportunities&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Instead, Slurm answers:&lt;/p&gt;

&lt;blockquote&gt;
&lt;p&gt;"How can I execute every compute job as efficiently as possible?"&lt;/p&gt;
&lt;/blockquote&gt;

&lt;p&gt;For HPC environments, this distinction is extremely important.&lt;/p&gt;




&lt;h2&gt;
  
  
  GPU Management
&lt;/h2&gt;

&lt;p&gt;AI workloads live and die by GPU utilization.&lt;/p&gt;

&lt;h3&gt;
  
  
  Kubernetes
&lt;/h3&gt;

&lt;p&gt;GPU support comes from:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;NVIDIA Device Plugin&lt;/li&gt;
&lt;li&gt;GPU Operator&lt;/li&gt;
&lt;li&gt;MIG support&lt;/li&gt;
&lt;li&gt;Device sharing&lt;/li&gt;
&lt;li&gt;Dynamic provisioning&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Excellent for:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;AI inference&lt;/li&gt;
&lt;li&gt;Model serving&lt;/li&gt;
&lt;li&gt;MLOps pipelines&lt;/li&gt;
&lt;li&gt;Kubernetes native AI platforms&lt;/li&gt;
&lt;/ul&gt;




&lt;h3&gt;
  
  
  Slurm
&lt;/h3&gt;

&lt;p&gt;GPU scheduling has been part of HPC for years.&lt;/p&gt;

&lt;p&gt;It supports:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;GRES&lt;/li&gt;
&lt;li&gt;GPU affinity&lt;/li&gt;
&lt;li&gt;Exclusive GPU allocation&lt;/li&gt;
&lt;li&gt;Multi node GPU jobs&lt;/li&gt;
&lt;li&gt;GPU topology awareness&lt;/li&gt;
&lt;li&gt;CUDA aware scheduling&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Large distributed training jobs typically integrate naturally with Slurm.&lt;/p&gt;




&lt;h2&gt;
  
  
  Multi node Distributed Training
&lt;/h2&gt;

&lt;p&gt;Modern LLM training often spans dozens or even thousands of GPUs.&lt;/p&gt;

&lt;h3&gt;
  
  
  Kubernetes
&lt;/h3&gt;

&lt;p&gt;Possible using:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Kubeflow&lt;/li&gt;
&lt;li&gt;Ray&lt;/li&gt;
&lt;li&gt;Volcano Scheduler&lt;/li&gt;
&lt;li&gt;MPI Operator&lt;/li&gt;
&lt;li&gt;Kueue&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;While these projects have matured significantly, distributed AI training often requires additional components beyond core Kubernetes.&lt;/p&gt;




&lt;h3&gt;
  
  
  Slurm
&lt;/h3&gt;

&lt;p&gt;Distributed workloads are native.&lt;/p&gt;

&lt;p&gt;Launching thousands of MPI processes is as simple as:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight shell"&gt;&lt;code&gt;srun &lt;span class="nt"&gt;-N&lt;/span&gt; 64 &lt;span class="nt"&gt;-n&lt;/span&gt; 512 ./application
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;Or GPU training:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight shell"&gt;&lt;code&gt;srun torchrun ...
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;MPI, NCCL, UCX, and InfiniBand integrate naturally with Slurm environments.&lt;/p&gt;




&lt;h2&gt;
  
  
  Networking
&lt;/h2&gt;

&lt;p&gt;High performance networking is another major differentiator.&lt;/p&gt;

&lt;h3&gt;
  
  
  Kubernetes
&lt;/h3&gt;

&lt;p&gt;Usually designed around:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;CNI plugins&lt;/li&gt;
&lt;li&gt;Overlay networks&lt;/li&gt;
&lt;li&gt;Service meshes&lt;/li&gt;
&lt;li&gt;Network policies&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Although RDMA and InfiniBand are supported, they often require additional configuration.&lt;/p&gt;




&lt;h3&gt;
  
  
  Slurm
&lt;/h3&gt;

&lt;p&gt;Designed for clusters using:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;InfiniBand&lt;/li&gt;
&lt;li&gt;HDR/NDR fabrics&lt;/li&gt;
&lt;li&gt;RoCE&lt;/li&gt;
&lt;li&gt;UCX&lt;/li&gt;
&lt;li&gt;MPI&lt;/li&gt;
&lt;li&gt;Low latency communication&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Network performance is treated as a first class citizen.&lt;/p&gt;




&lt;h2&gt;
  
  
  Job Lifecycle
&lt;/h2&gt;

&lt;h3&gt;
  
  
  Kubernetes
&lt;/h3&gt;

&lt;p&gt;Applications often run continuously.&lt;/p&gt;

&lt;p&gt;Examples:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Web APIs&lt;/li&gt;
&lt;li&gt;Databases&lt;/li&gt;
&lt;li&gt;AI inference servers&lt;/li&gt;
&lt;li&gt;Monitoring services&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Pods restart automatically after failure.&lt;/p&gt;




&lt;h3&gt;
  
  
  Slurm
&lt;/h3&gt;

&lt;p&gt;Jobs are temporary.&lt;/p&gt;

&lt;p&gt;Typical lifecycle:&lt;/p&gt;

&lt;ol&gt;
&lt;li&gt;Submit&lt;/li&gt;
&lt;li&gt;Queue&lt;/li&gt;
&lt;li&gt;Allocate resources&lt;/li&gt;
&lt;li&gt;Execute&lt;/li&gt;
&lt;li&gt;Finish&lt;/li&gt;
&lt;li&gt;Release resources&lt;/li&gt;
&lt;/ol&gt;

&lt;p&gt;This matches scientific computing perfectly.&lt;/p&gt;




&lt;h2&gt;
  
  
  Auto Scaling
&lt;/h2&gt;

&lt;h3&gt;
  
  
  Kubernetes
&lt;/h3&gt;

&lt;p&gt;One of Kubernetes' biggest strengths.&lt;/p&gt;

&lt;p&gt;Supports:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Horizontal Pod Autoscaler&lt;/li&gt;
&lt;li&gt;Vertical Pod Autoscaler&lt;/li&gt;
&lt;li&gt;Cluster Autoscaler&lt;/li&gt;
&lt;li&gt;Cloud auto provisioning&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Ideal for dynamic workloads.&lt;/p&gt;




&lt;h3&gt;
  
  
  Slurm
&lt;/h3&gt;

&lt;p&gt;Traditionally built for fixed clusters.&lt;/p&gt;

&lt;p&gt;However, cloud integrations now allow elastic compute using:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Azure CycleCloud&lt;/li&gt;
&lt;li&gt;AWS ParallelCluster&lt;/li&gt;
&lt;li&gt;AWS PCS&lt;/li&gt;
&lt;li&gt;Google Cloud HPC Toolkit&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Nodes can automatically start and stop based on queue demand.&lt;/p&gt;




&lt;h2&gt;
  
  
  Ecosystem
&lt;/h2&gt;

&lt;h3&gt;
  
  
  Kubernetes Ecosystem
&lt;/h3&gt;

&lt;p&gt;The ecosystem is enormous.&lt;/p&gt;

&lt;p&gt;Popular AI tools include:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Kubeflow&lt;/li&gt;
&lt;li&gt;MLflow&lt;/li&gt;
&lt;li&gt;Argo Workflows&lt;/li&gt;
&lt;li&gt;Ray&lt;/li&gt;
&lt;li&gt;KServe&lt;/li&gt;
&lt;li&gt;Prometheus&lt;/li&gt;
&lt;li&gt;Grafana&lt;/li&gt;
&lt;li&gt;Istio&lt;/li&gt;
&lt;li&gt;Helm&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Cloud providers offer fully managed Kubernetes services.&lt;/p&gt;




&lt;h3&gt;
  
  
  Slurm Ecosystem
&lt;/h3&gt;

&lt;p&gt;Focused on HPC.&lt;/p&gt;

&lt;p&gt;Common integrations include:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;OpenMPI&lt;/li&gt;
&lt;li&gt;MPICH&lt;/li&gt;
&lt;li&gt;UCX&lt;/li&gt;
&lt;li&gt;BeeGFS&lt;/li&gt;
&lt;li&gt;Lustre&lt;/li&gt;
&lt;li&gt;GPFS&lt;/li&gt;
&lt;li&gt;Spack&lt;/li&gt;
&lt;li&gt;Lmod&lt;/li&gt;
&lt;li&gt;Apptainer (Singularity)&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;These tools are standard across many research institutions and supercomputing centers.&lt;/p&gt;




&lt;h2&gt;
  
  
  Performance
&lt;/h2&gt;

&lt;p&gt;For tightly coupled HPC jobs, Slurm generally provides better performance because it understands:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;CPU topology&lt;/li&gt;
&lt;li&gt;NUMA domains&lt;/li&gt;
&lt;li&gt;GPU locality&lt;/li&gt;
&lt;li&gt;Network topology&lt;/li&gt;
&lt;li&gt;Exclusive allocations&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Kubernetes introduces additional abstraction layers that are acceptable for cloud applications but may add complexity for latency sensitive HPC workloads.&lt;/p&gt;

&lt;p&gt;For AI inference or microservices, Kubernetes is usually the stronger choice.&lt;/p&gt;




&lt;h2&gt;
  
  
  Operational Complexity
&lt;/h2&gt;

&lt;div class="table-wrapper-paragraph"&gt;&lt;table&gt;
&lt;thead&gt;
&lt;tr&gt;
&lt;th&gt;Kubernetes&lt;/th&gt;
&lt;th&gt;Slurm&lt;/th&gt;
&lt;/tr&gt;
&lt;/thead&gt;
&lt;tbody&gt;
&lt;tr&gt;
&lt;td&gt;Steeper learning curve for cloud native concepts&lt;/td&gt;
&lt;td&gt;Easier for traditional HPC administrators&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;Large ecosystem&lt;/td&gt;
&lt;td&gt;Focused ecosystem&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;Many moving parts&lt;/td&gt;
&lt;td&gt;Smaller control plane&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;Excellent API ecosystem&lt;/td&gt;
&lt;td&gt;Excellent batch scheduling&lt;/td&gt;
&lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;&lt;/div&gt;

&lt;p&gt;Both platforms require expertise, but in different domains.&lt;/p&gt;




&lt;h2&gt;
  
  
  Can They Work Together?
&lt;/h2&gt;

&lt;p&gt;Absolutely.&lt;/p&gt;

&lt;p&gt;Many organizations no longer choose one over the other.&lt;/p&gt;

&lt;p&gt;A common architecture looks like this:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;
&lt;p&gt;Kubernetes for:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;AI inference&lt;/li&gt;
&lt;li&gt;APIs&lt;/li&gt;
&lt;li&gt;MLOps&lt;/li&gt;
&lt;li&gt;Jupyter notebooks&lt;/li&gt;
&lt;li&gt;Web services&lt;/li&gt;
&lt;li&gt;Model deployment&lt;/li&gt;
&lt;/ul&gt;
&lt;/li&gt;
&lt;li&gt;
&lt;p&gt;Slurm for:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;AI training&lt;/li&gt;
&lt;li&gt;HPC simulations&lt;/li&gt;
&lt;li&gt;MPI applications&lt;/li&gt;
&lt;li&gt;Large GPU clusters&lt;/li&gt;
&lt;li&gt;Scientific computing&lt;/li&gt;
&lt;li&gt;Batch processing&lt;/li&gt;
&lt;/ul&gt;
&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Some environments even allow Kubernetes to submit workloads into Slurm managed clusters, combining the flexibility of cloud native tooling with the efficiency of HPC scheduling.&lt;/p&gt;




&lt;h2&gt;
  
  
  Which One Should You Choose?
&lt;/h2&gt;

&lt;div class="table-wrapper-paragraph"&gt;&lt;table&gt;
&lt;thead&gt;
&lt;tr&gt;
&lt;th&gt;Workload&lt;/th&gt;
&lt;th&gt;Best Choice&lt;/th&gt;
&lt;/tr&gt;
&lt;/thead&gt;
&lt;tbody&gt;
&lt;tr&gt;
&lt;td&gt;Web applications&lt;/td&gt;
&lt;td&gt;Kubernetes&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;AI inference&lt;/td&gt;
&lt;td&gt;Kubernetes&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;MLOps pipelines&lt;/td&gt;
&lt;td&gt;Kubernetes&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;Scientific simulations&lt;/td&gt;
&lt;td&gt;Slurm&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;MPI applications&lt;/td&gt;
&lt;td&gt;Slurm&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;CFD&lt;/td&gt;
&lt;td&gt;Slurm&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;Computational chemistry&lt;/td&gt;
&lt;td&gt;Slurm&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;Large scale distributed AI training&lt;/td&gt;
&lt;td&gt;Slurm&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;Mixed enterprise AI platform&lt;/td&gt;
&lt;td&gt;Kubernetes + Slurm&lt;/td&gt;
&lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;&lt;/div&gt;




&lt;h2&gt;
  
  
  Final Thoughts
&lt;/h2&gt;

&lt;p&gt;Kubernetes and Slurm are not competitors in the traditional sense. They were designed to solve different problems, and both have evolved to support modern AI infrastructure.&lt;/p&gt;

&lt;p&gt;If your primary focus is cloud native applications, model serving, and scalable AI services, Kubernetes provides unmatched flexibility and ecosystem support.&lt;/p&gt;

&lt;p&gt;If your goal is to maximize utilization of expensive CPUs and GPUs for tightly coupled scientific workloads or large scale distributed AI training, Slurm remains the gold standard.&lt;/p&gt;

&lt;p&gt;As AI platforms continue to grow, the most effective architectures increasingly combine the strengths of both technologies rather than forcing a choice between them.&lt;/p&gt;

&lt;p&gt;The future of AI infrastructure is not &lt;strong&gt;Kubernetes versus Slurm&lt;/strong&gt;. It's knowing when to use each one.&lt;/p&gt;

</description>
      <category>ai</category>
      <category>kubernetes</category>
      <category>hpc</category>
      <category>productivity</category>
    </item>
    <item>
      <title>Why AI Clusters Fail Even When GPUs Are Idle</title>
      <dc:creator>Muhammad Zubair Bin Akbar</dc:creator>
      <pubDate>Fri, 26 Jun 2026 22:50:48 +0000</pubDate>
      <link>https://dev.to/zubairakbar/why-ai-clusters-fail-even-when-gpus-are-idle-5hdb</link>
      <guid>https://dev.to/zubairakbar/why-ai-clusters-fail-even-when-gpus-are-idle-5hdb</guid>
      <description>&lt;p&gt;When organizations build AI infrastructure, GPUs usually get all the attention.&lt;/p&gt;

&lt;p&gt;Teams invest in the latest accelerators, add high speed networking, and expect training jobs to scale effortlessly. Yet many AI clusters deliver disappointing performance despite having powerful hardware.&lt;/p&gt;

&lt;p&gt;The surprising part?&lt;/p&gt;

&lt;p&gt;The GPUs are often idle.&lt;/p&gt;

&lt;p&gt;GPU monitoring dashboards may show utilization dropping to 20%, 10%, or even 0% between bursts of activity. At first glance, this looks like a GPU problem, but in most cases it isn’t.&lt;/p&gt;

&lt;p&gt;The GPUs are simply waiting.&lt;/p&gt;

&lt;p&gt;Let’s understand why this happens and how HPC principles can help solve it.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  The GPU Is Only One Part of the Pipeline
&lt;/h2&gt;

&lt;p&gt;Think of an AI training job like an assembly line.&lt;/p&gt;

&lt;p&gt;Before a GPU can process a batch, several things must happen:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Data must be read from storage.&lt;/li&gt;
&lt;li&gt;Files may need decompression.&lt;/li&gt;
&lt;li&gt;Images or text must be preprocessed.&lt;/li&gt;
&lt;li&gt;Data is copied into system memory.&lt;/li&gt;
&lt;li&gt;Finally, it is transferred to GPU memory.&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Only after all these steps can computation begin.&lt;/p&gt;

&lt;p&gt;If any stage becomes slow, the GPU has nothing to process and simply waits.&lt;/p&gt;

&lt;p&gt;Imagine buying the fastest race car in the world but fueling it with a tiny garden hose.&lt;/p&gt;

&lt;p&gt;The car isn’t slow.&lt;/p&gt;

&lt;p&gt;The fuel delivery is.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  Common Reasons GPUs Sit Idle
&lt;/h2&gt;

&lt;h3&gt;
  
  
  1. Slow Storage Performance
&lt;/h3&gt;

&lt;p&gt;Large AI datasets often consist of millions of small files.&lt;/p&gt;

&lt;p&gt;If the storage system cannot deliver data quickly enough, GPUs finish processing one batch before the next is ready.&lt;/p&gt;

&lt;p&gt;This is especially common when:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Using network-attached storage&lt;/li&gt;
&lt;li&gt;Reading millions of tiny files&lt;/li&gt;
&lt;li&gt;Storage bandwidth is shared among many users&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;The result is expensive GPUs waiting for data.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h3&gt;
  
  
  2. Data Loading Becomes the Bottleneck
&lt;/h3&gt;

&lt;p&gt;Most deep learning frameworks rely on data loader workers running on CPUs.&lt;/p&gt;

&lt;p&gt;These workers:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Read files&lt;/li&gt;
&lt;li&gt;Decode images&lt;/li&gt;
&lt;li&gt;Tokenize text&lt;/li&gt;
&lt;li&gt;Apply augmentations&lt;/li&gt;
&lt;li&gt;Prepare training batches&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;If there are too few workers or the CPUs are overloaded, GPU utilization drops dramatically.&lt;/p&gt;

&lt;p&gt;Many people immediately reduce batch size or change GPU settings, when the actual bottleneck is the CPU.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h3&gt;
  
  
  3. CPUs Cannot Keep Up
&lt;/h3&gt;

&lt;p&gt;Modern GPUs are incredibly fast.&lt;/p&gt;

&lt;p&gt;Preparing data fast enough to feed them requires powerful CPUs.&lt;/p&gt;

&lt;p&gt;If CPU cores are fully occupied with preprocessing tasks, GPUs repeatedly wait for the next batch.&lt;/p&gt;

&lt;p&gt;This becomes more noticeable as GPU performance increases.&lt;/p&gt;

&lt;p&gt;Ironically, upgrading GPUs without upgrading CPUs can actually expose new bottlenecks.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h3&gt;
  
  
  4. Poor Network Performance
&lt;/h3&gt;

&lt;p&gt;Distributed training depends heavily on communication.&lt;/p&gt;

&lt;p&gt;Gradients, parameters, and synchronization data constantly move between nodes.&lt;/p&gt;

&lt;p&gt;If the network is slow or congested:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;GPUs complete computation.&lt;/li&gt;
&lt;li&gt;They wait for synchronization.&lt;/li&gt;
&lt;li&gt;Training stalls before the next iteration begins.&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;This is why technologies like InfiniBand, Omni Path, and RDMA are so valuable in AI clusters.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h3&gt;
  
  
  5. Small Batch Sizes
&lt;/h3&gt;

&lt;p&gt;Sometimes the workload itself is too small.&lt;/p&gt;

&lt;p&gt;If each GPU receives only a tiny amount of work:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Computation finishes quickly.&lt;/li&gt;
&lt;li&gt;Communication overhead dominates.&lt;/li&gt;
&lt;li&gt;GPUs spend more time waiting than computing.&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Increasing batch size or improving workload distribution often improves utilization.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h3&gt;
  
  
  6. Filesystem Contention
&lt;/h3&gt;

&lt;p&gt;In shared HPC environments, dozens or hundreds of users may access the same storage simultaneously.&lt;/p&gt;

&lt;p&gt;Even if a single training job performs well during testing, production workloads may compete for:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Storage bandwidth&lt;/li&gt;
&lt;li&gt;Metadata operations&lt;/li&gt;
&lt;li&gt;Shared filesystem resources&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;As contention grows, GPUs spend more time waiting for IO.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  The Hidden Cost of Idle GPUs
&lt;/h2&gt;

&lt;p&gt;Imagine an organization with:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;64 GPUs&lt;/li&gt;
&lt;li&gt;Each GPU costs thousands of dollars&lt;/li&gt;
&lt;li&gt;Jobs run continuously&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;If GPU utilization averages only 40%, then more than half of the available computing power is effectively wasted.&lt;/p&gt;

&lt;p&gt;Organizations often respond by purchasing more GPUs.&lt;/p&gt;

&lt;p&gt;In reality, fixing storage, networking, scheduling, or data pipelines could provide a much larger performance improvement at a fraction of the cost.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  How HPC Practices Help
&lt;/h2&gt;

&lt;p&gt;Traditional HPC has dealt with resource bottlenecks for decades.&lt;/p&gt;

&lt;p&gt;Many of the same principles improve AI workloads.&lt;/p&gt;

&lt;p&gt;Optimize Data Locality&lt;/p&gt;

&lt;p&gt;Store frequently used datasets close to compute nodes whenever possible.&lt;/p&gt;

&lt;p&gt;Reducing unnecessary data movement keeps GPUs busy.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  Improve Storage Performance
&lt;/h2&gt;

&lt;p&gt;Use parallel filesystems, local NVMe storage, or intelligent caching for large datasets.&lt;/p&gt;

&lt;p&gt;Faster data access directly translates into higher GPU utilization.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  Tune Data Loaders
&lt;/h2&gt;

&lt;p&gt;Experiment with:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Number of worker processes&lt;/li&gt;
&lt;li&gt;Prefetching&lt;/li&gt;
&lt;li&gt;Pinned memory&lt;/li&gt;
&lt;li&gt;Batch preparation&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Small configuration changes can produce significant improvements.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  Balance CPU and GPU Resources
&lt;/h2&gt;

&lt;p&gt;More GPUs are not always the answer.&lt;/p&gt;

&lt;p&gt;Ensure CPUs have enough cores and memory bandwidth to continuously feed the accelerators.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  Use High Speed Interconnects
&lt;/h2&gt;

&lt;p&gt;Distributed AI workloads benefit greatly from low latency networking.&lt;/p&gt;

&lt;p&gt;Reducing communication delays allows GPUs to spend more time computing.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  Monitor the Entire Pipeline
&lt;/h2&gt;

&lt;p&gt;Instead of monitoring only GPU utilization, observe:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;CPU usage&lt;/li&gt;
&lt;li&gt;Disk throughput&lt;/li&gt;
&lt;li&gt;Network bandwidth&lt;/li&gt;
&lt;li&gt;Filesystem latency&lt;/li&gt;
&lt;li&gt;Memory utilization&lt;/li&gt;
&lt;li&gt;Data loading times&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;The real bottleneck is often outside the GPU.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  A Real World Example
&lt;/h2&gt;

&lt;p&gt;Consider a cluster with eight GPUs training an image classification model.&lt;/p&gt;

&lt;p&gt;During monitoring:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;GPU utilization averages only 35%.&lt;/li&gt;
&lt;li&gt;CPUs remain close to 100%.&lt;/li&gt;
&lt;li&gt;Storage shows heavy read activity.&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;The instinct might be to upgrade the GPUs.&lt;/p&gt;

&lt;p&gt;Instead, the team moves the dataset to local NVMe storage and increases the number of data loader workers.&lt;/p&gt;

&lt;p&gt;GPU utilization jumps to over 90%.&lt;/p&gt;

&lt;p&gt;No new GPUs were purchased.&lt;/p&gt;

&lt;p&gt;The bottleneck was never the accelerators.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  Final Thoughts
&lt;/h2&gt;

&lt;p&gt;AI performance is about far more than GPUs.&lt;/p&gt;

&lt;p&gt;A training job is only as fast as its slowest component. Storage, CPUs, networking, filesystems, and data pipelines all contribute to overall performance.&lt;/p&gt;

&lt;p&gt;When GPUs appear idle, they’re usually waiting for the rest of the system to catch up.&lt;/p&gt;

&lt;p&gt;Understanding the entire infrastructure, rather than focusing solely on accelerators, is what separates a well designed AI cluster from an expensive collection of underutilized hardware.&lt;/p&gt;

&lt;p&gt;The next time someone says, &lt;em&gt;“Our GPUs are slow”&lt;/em&gt;, take a closer look.&lt;/p&gt;

&lt;p&gt;The GPUs may simply be waiting for everyone else.&lt;/p&gt;

</description>
      <category>ai</category>
      <category>hpc</category>
      <category>productivity</category>
      <category>architecture</category>
    </item>
    <item>
      <title>From HPC Clusters to AI Training: How High Performance Computing Powers Modern AI</title>
      <dc:creator>Muhammad Zubair Bin Akbar</dc:creator>
      <pubDate>Mon, 25 May 2026 18:04:02 +0000</pubDate>
      <link>https://dev.to/zubairakbar/from-hpc-clusters-to-ai-training-how-high-performance-computing-powers-modern-ai-92e</link>
      <guid>https://dev.to/zubairakbar/from-hpc-clusters-to-ai-training-how-high-performance-computing-powers-modern-ai-92e</guid>
      <description>&lt;p&gt;Artificial Intelligence and Machine Learning workloads continue to grow rapidly. Training modern AI models now requires massive compute power, large memory capacity, fast storage, and efficient networking. This is where High Performance Computing (HPC) becomes important.&lt;/p&gt;

&lt;p&gt;HPC is no longer limited to scientific simulations or academic research. Today, it plays a major role in AI and ML development across industries including healthcare, finance, automotive, cybersecurity, and research.&lt;/p&gt;

&lt;h2&gt;
  
  
  What is HPC?
&lt;/h2&gt;

&lt;p&gt;High Performance Computing refers to a group of powerful servers connected together to work as a single system. These systems are designed to process extremely large workloads much faster than traditional servers or desktop machines.&lt;/p&gt;

&lt;p&gt;An HPC cluster usually includes:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Multiple compute nodes&lt;/li&gt;
&lt;li&gt;High core count CPUs&lt;/li&gt;
&lt;li&gt;GPUs for acceleration&lt;/li&gt;
&lt;li&gt;Fast parallel storage&lt;/li&gt;
&lt;li&gt;High speed interconnects like InfiniBand or Omni Path&lt;/li&gt;
&lt;li&gt;Resource managers such as Slurm&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Instead of running workloads on a single machine, HPC distributes tasks across many nodes to reduce execution time and improve performance.&lt;/p&gt;

&lt;h2&gt;
  
  
  Why AI and ML Need HPC
&lt;/h2&gt;

&lt;p&gt;AI and ML training workloads are computationally expensive. Modern models process massive datasets and perform billions or even trillions of calculations during training.&lt;/p&gt;

&lt;p&gt;A normal server may struggle with:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Large language model training&lt;/li&gt;
&lt;li&gt;Deep learning workloads&lt;/li&gt;
&lt;li&gt;Distributed GPU training&lt;/li&gt;
&lt;li&gt;Processing huge datasets&lt;/li&gt;
&lt;li&gt;Real time inference at scale&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;HPC solves these limitations by providing scalable compute resources and parallel processing capabilities.&lt;/p&gt;

&lt;h2&gt;
  
  
  GPU Acceleration in AI Training
&lt;/h2&gt;

&lt;p&gt;GPUs are one of the biggest reasons HPC is widely used in AI.&lt;/p&gt;

&lt;p&gt;Unlike CPUs, GPUs can process thousands of operations simultaneously. This makes them ideal for matrix calculations and tensor operations used in deep learning frameworks such as:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;PyTorch&lt;/li&gt;
&lt;li&gt;TensorFlow&lt;/li&gt;
&lt;li&gt;JAX&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;In HPC environments, multiple GPUs can work together across different compute nodes using technologies like:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;NVIDIA NCCL&lt;/li&gt;
&lt;li&gt;CUDA&lt;/li&gt;
&lt;li&gt;MPI&lt;/li&gt;
&lt;li&gt;RDMA&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;This allows AI models to train significantly faster compared to single machine setups.&lt;/p&gt;

&lt;h2&gt;
  
  
  Distributed Training
&lt;/h2&gt;

&lt;p&gt;Training large AI models on one GPU is often impossible because of memory and compute limitations.&lt;/p&gt;

&lt;p&gt;HPC clusters enable distributed training where:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Data is split across multiple GPUs&lt;/li&gt;
&lt;li&gt;Workloads are shared between nodes&lt;/li&gt;
&lt;li&gt;Training happens in parallel&lt;/li&gt;
&lt;li&gt;Results are synchronized efficiently&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Distributed training helps reduce training time from weeks to days or even hours.&lt;/p&gt;

&lt;p&gt;For example:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;A single GPU may take several weeks to train a large model&lt;/li&gt;
&lt;li&gt;An HPC cluster with hundreds of GPUs can complete the same training much faster&lt;/li&gt;
&lt;/ul&gt;

&lt;h2&gt;
  
  
  Importance of High Speed Networking
&lt;/h2&gt;

&lt;p&gt;AI workloads generate constant communication between GPUs and compute nodes.&lt;/p&gt;

&lt;p&gt;Slow networking creates bottlenecks and reduces performance. HPC clusters use low latency high bandwidth interconnects such as:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;InfiniBand&lt;/li&gt;
&lt;li&gt;Omni Path&lt;/li&gt;
&lt;li&gt;RoCE&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;These technologies help accelerate:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;GPU to GPU communication&lt;/li&gt;
&lt;li&gt;Distributed storage access&lt;/li&gt;
&lt;li&gt;MPI communication&lt;/li&gt;
&lt;li&gt;Parameter synchronization&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Low latency networking is critical for efficient AI scaling.&lt;/p&gt;

&lt;h2&gt;
  
  
  Storage Requirements for AI
&lt;/h2&gt;

&lt;p&gt;AI training datasets can range from gigabytes to petabytes.&lt;/p&gt;

&lt;p&gt;Traditional storage solutions may not provide enough throughput for parallel workloads. HPC environments often use:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Lustre&lt;/li&gt;
&lt;li&gt;BeeGFS&lt;/li&gt;
&lt;li&gt;GPFS&lt;/li&gt;
&lt;li&gt;NVMe based storage&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;These parallel filesystems allow multiple nodes to read and write data simultaneously without major bottlenecks.&lt;/p&gt;

&lt;h2&gt;
  
  
  Job Scheduling and Resource Management
&lt;/h2&gt;

&lt;p&gt;In shared HPC environments, multiple users run workloads at the same time.&lt;/p&gt;

&lt;p&gt;Schedulers like Slurm help manage resources efficiently by:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Allocating CPUs and GPUs&lt;/li&gt;
&lt;li&gt;Managing job queues&lt;/li&gt;
&lt;li&gt;Enforcing fair usage&lt;/li&gt;
&lt;li&gt;Optimizing cluster utilization&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;AI researchers can submit training jobs, reserve GPUs, monitor workloads, and scale resources dynamically.&lt;/p&gt;

&lt;h2&gt;
  
  
  Common AI Workloads Running on HPC
&lt;/h2&gt;

&lt;p&gt;HPC clusters are commonly used for:&lt;/p&gt;

&lt;h3&gt;
  
  
  Deep Learning Training
&lt;/h3&gt;

&lt;p&gt;Training neural networks for image recognition, NLP, and recommendation systems.&lt;/p&gt;

&lt;h3&gt;
  
  
  Large Language Models
&lt;/h3&gt;

&lt;p&gt;Training and fine tuning transformer based models.&lt;/p&gt;

&lt;h3&gt;
  
  
  Computer Vision
&lt;/h3&gt;

&lt;p&gt;Object detection, segmentation, and video analytics.&lt;/p&gt;

&lt;h3&gt;
  
  
  Scientific AI
&lt;/h3&gt;

&lt;p&gt;Using AI for climate modeling, genomics, and physics research.&lt;/p&gt;

&lt;h3&gt;
  
  
  Reinforcement Learning
&lt;/h3&gt;

&lt;p&gt;Large scale simulation based training environments.&lt;/p&gt;

&lt;h2&gt;
  
  
  Benefits of Using HPC for AI
&lt;/h2&gt;

&lt;h3&gt;
  
  
  Faster Training
&lt;/h3&gt;

&lt;p&gt;Massive parallelism reduces overall training time.&lt;/p&gt;

&lt;h3&gt;
  
  
  Scalability
&lt;/h3&gt;

&lt;p&gt;Resources can scale from a few GPUs to thousands.&lt;/p&gt;

&lt;h3&gt;
  
  
  Better Resource Utilization
&lt;/h3&gt;

&lt;p&gt;Shared infrastructure improves efficiency and reduces hardware waste.&lt;/p&gt;

&lt;h3&gt;
  
  
  Improved Collaboration
&lt;/h3&gt;

&lt;p&gt;Researchers and teams can share compute infrastructure securely.&lt;/p&gt;

&lt;h3&gt;
  
  
  Support for Large Models
&lt;/h3&gt;

&lt;p&gt;HPC makes training large modern AI models practical.&lt;/p&gt;

&lt;h2&gt;
  
  
  Challenges in AI HPC Environments
&lt;/h2&gt;

&lt;p&gt;Despite the advantages, AI on HPC also introduces challenges:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;GPU memory limitations&lt;/li&gt;
&lt;li&gt;Network bottlenecks&lt;/li&gt;
&lt;li&gt;Storage throughput issues&lt;/li&gt;
&lt;li&gt;Distributed training complexity&lt;/li&gt;
&lt;li&gt;Power and cooling requirements&lt;/li&gt;
&lt;li&gt;Software compatibility&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Proper cluster design and tuning are important for achieving good AI performance.&lt;/p&gt;

&lt;h2&gt;
  
  
  The Future of HPC and AI
&lt;/h2&gt;

&lt;p&gt;AI and HPC are becoming increasingly connected. Many modern supercomputers are now designed primarily for AI workloads.&lt;/p&gt;

&lt;p&gt;Future HPC systems will continue focusing on:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Larger GPU clusters&lt;/li&gt;
&lt;li&gt;Faster interconnects&lt;/li&gt;
&lt;li&gt;AI optimized processors&lt;/li&gt;
&lt;li&gt;Energy efficient computing&lt;/li&gt;
&lt;li&gt;Hybrid cloud HPC environments&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;As AI models continue growing, HPC will remain one of the core technologies powering innovation.&lt;/p&gt;

&lt;h2&gt;
  
  
  Final Thoughts
&lt;/h2&gt;

&lt;p&gt;High Performance Computing has become one of the most important foundations for modern AI and Machine Learning workloads.&lt;/p&gt;

&lt;p&gt;From distributed GPU training to high speed networking and parallel storage, HPC provides the infrastructure needed to train and run advanced AI models efficiently at scale.&lt;/p&gt;

&lt;p&gt;As AI adoption continues increasing across industries, the role of HPC will only become more important in the years ahead.&lt;/p&gt;

</description>
      <category>ai</category>
      <category>machinelearning</category>
      <category>hpc</category>
      <category>performance</category>
    </item>
    <item>
      <title>CPU Pinning and Affinity in HPC: Why Performance Changes Drastically</title>
      <dc:creator>Muhammad Zubair Bin Akbar</dc:creator>
      <pubDate>Sat, 16 May 2026 18:58:33 +0000</pubDate>
      <link>https://dev.to/zubairakbar/cpu-pinning-and-affinity-in-hpc-why-performance-changes-drastically-5f5j</link>
      <guid>https://dev.to/zubairakbar/cpu-pinning-and-affinity-in-hpc-why-performance-changes-drastically-5f5j</guid>
      <description>&lt;p&gt;In HPC environments, users often notice something confusing:&lt;/p&gt;

&lt;p&gt;The same application, same input, and same number of CPUs can produce very different performance results across runs.&lt;/p&gt;

&lt;p&gt;One of the biggest reasons behind this is CPU pinning and CPU affinity.&lt;/p&gt;

&lt;p&gt;Without proper CPU placement, processes can bounce between cores, compete for cache, and suffer from NUMA penalties. In large parallel workloads, this can drastically reduce performance.&lt;/p&gt;

&lt;p&gt;This blog explains what CPU pinning and affinity are, why they matter in HPC, and how they impact real workloads.&lt;/p&gt;




&lt;h2&gt;
  
  
  What Is CPU Affinity?
&lt;/h2&gt;

&lt;p&gt;CPU affinity controls which CPU cores a process or thread is allowed to run on.&lt;/p&gt;

&lt;p&gt;The operating system scheduler can still move the process between the allowed cores, but only within that defined CPU set.&lt;/p&gt;

&lt;h3&gt;
  
  
  For example:
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;A process may be allowed to run only on cores 0 to 7&lt;/li&gt;
&lt;li&gt;The scheduler can move it between those cores if needed&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Affinity helps improve cache locality and reduces unnecessary movement across the entire system.&lt;/p&gt;




&lt;h2&gt;
  
  
  What Is CPU Pinning?
&lt;/h2&gt;

&lt;p&gt;CPU pinning is the actual act of locking a process or thread to a CPU core.&lt;/p&gt;

&lt;p&gt;In HPC clusters, schedulers like Slurm often handle this automatically through CPU binding options.&lt;/p&gt;

&lt;h3&gt;
  
  
  For example:
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;MPI rank 0 stays on core 0&lt;/li&gt;
&lt;li&gt;MPI rank 1 stays on core 1&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;This minimizes CPU migrations and provides more predictable performance for HPC workloads.&lt;/p&gt;

&lt;h3&gt;
  
  
  Pinning ensures:
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;Better cache locality&lt;/li&gt;
&lt;li&gt;Reduced scheduler overhead&lt;/li&gt;
&lt;li&gt;Predictable performance&lt;/li&gt;
&lt;li&gt;Lower NUMA latency&lt;/li&gt;
&lt;li&gt;Reduced context switching&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Without pinning, Linux may move tasks between cores frequently depending on system activity.&lt;/p&gt;




&lt;h2&gt;
  
  
  Why Performance Changes So Much
&lt;/h2&gt;

&lt;p&gt;Modern HPC nodes are complex.&lt;/p&gt;

&lt;h3&gt;
  
  
  A single node may contain:
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;Multiple CPU sockets&lt;/li&gt;
&lt;li&gt;NUMA regions&lt;/li&gt;
&lt;li&gt;Shared and private caches&lt;/li&gt;
&lt;li&gt;Hyperthreading&lt;/li&gt;
&lt;li&gt;Hundreds of logical CPUs&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;When processes move randomly between CPUs, several problems appear.&lt;/p&gt;




&lt;h2&gt;
  
  
  Cache Locality Problems
&lt;/h2&gt;

&lt;p&gt;CPUs rely heavily on cache memory.&lt;/p&gt;

&lt;p&gt;If a thread keeps running on the same core, cached data remains available and execution becomes faster.&lt;/p&gt;

&lt;p&gt;When the thread migrates to another core:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Cache must be rebuilt&lt;/li&gt;
&lt;li&gt;Memory access latency increases&lt;/li&gt;
&lt;li&gt;CPU cycles are wasted&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;This becomes extremely expensive for tightly coupled MPI applications.&lt;/p&gt;




&lt;h2&gt;
  
  
  NUMA Effects
&lt;/h2&gt;

&lt;p&gt;NUMA stands for Non Uniform Memory Access.&lt;/p&gt;

&lt;p&gt;In multi socket systems, memory attached to the local CPU socket is faster than memory attached to another socket.&lt;/p&gt;

&lt;p&gt;If a process runs on Socket 0 but accesses memory allocated on Socket 1:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Memory latency increases&lt;/li&gt;
&lt;li&gt;Bandwidth decreases&lt;/li&gt;
&lt;li&gt;Application performance drops&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;This is one of the most common reasons HPC jobs scale poorly.&lt;/p&gt;




&lt;h2&gt;
  
  
  Example of Bad CPU Placement
&lt;/h2&gt;

&lt;p&gt;Consider a dual socket server:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Socket 0 → cores 0 to 31&lt;/li&gt;
&lt;li&gt;Socket 1 → cores 32 to 63&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;If an MPI application launches ranks without proper affinity:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Rank 0 may start on core 2&lt;/li&gt;
&lt;li&gt;Later move to core 40&lt;/li&gt;
&lt;li&gt;Then back to core 10&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Now the application suffers from:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Remote memory access&lt;/li&gt;
&lt;li&gt;Cache misses&lt;/li&gt;
&lt;li&gt;CPU migration overhead&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;The result can be a major slowdown even though CPU usage appears high.&lt;/p&gt;




&lt;h2&gt;
  
  
  MPI and CPU Binding
&lt;/h2&gt;

&lt;p&gt;MPI applications are very sensitive to where processes run on the CPU.&lt;/p&gt;

&lt;p&gt;If MPI ranks keep moving between cores:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Cache data gets lost&lt;/li&gt;
&lt;li&gt;Memory access becomes slower&lt;/li&gt;
&lt;li&gt;Communication latency increases&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;To avoid this, MPI runtimes and schedulers use CPU binding or pinning.&lt;/p&gt;

&lt;h3&gt;
  
  
  For example with Open MPI:
&lt;/h3&gt;



&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight shell"&gt;&lt;code&gt;mpirun &lt;span class="nt"&gt;--bind-to&lt;/span&gt; core &lt;span class="nt"&gt;--map-by&lt;/span&gt; socket ./app
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h3&gt;
  
  
  With Slurm:
&lt;/h3&gt;



&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight shell"&gt;&lt;code&gt;srun &lt;span class="nt"&gt;--cpu-bind&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;cores ./app
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;These settings keep MPI processes fixed to specific CPU cores, which usually provides more stable and faster performance in HPC workloads.&lt;/p&gt;




&lt;h2&gt;
  
  
  Hyperthreading Can Also Matter
&lt;/h2&gt;

&lt;p&gt;Some workloads perform poorly when pinned to logical CPUs instead of physical cores.&lt;/p&gt;

&lt;p&gt;For compute intensive applications:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Two threads sharing one physical core may compete for resources&lt;/li&gt;
&lt;li&gt;Floating point performance may decrease&lt;/li&gt;
&lt;li&gt;Memory bandwidth may become limited&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;This is why many HPC sites disable hyperthreading for production workloads.&lt;/p&gt;




&lt;h2&gt;
  
  
  Real World Performance Difference
&lt;/h2&gt;

&lt;p&gt;In many HPC benchmarks:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Proper CPU affinity can improve performance by 10% to 40%&lt;/li&gt;
&lt;li&gt;NUMA aware placement can reduce latency significantly&lt;/li&gt;
&lt;li&gt;Communication heavy MPI jobs benefit the most&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Applications such as:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;CFD solvers&lt;/li&gt;
&lt;li&gt;Molecular dynamics&lt;/li&gt;
&lt;li&gt;Finite element simulations&lt;/li&gt;
&lt;li&gt;AI training workloads&lt;/li&gt;
&lt;li&gt;Weather modeling&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;are highly sensitive to CPU placement.&lt;/p&gt;




&lt;h2&gt;
  
  
  How to Check CPU Affinity
&lt;/h2&gt;

&lt;p&gt;Useful Linux tools include:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight shell"&gt;&lt;code&gt;taskset &lt;span class="nt"&gt;-p&lt;/span&gt; &amp;lt;pid&amp;gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;





&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight shell"&gt;&lt;code&gt;numactl &lt;span class="nt"&gt;--show&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;





&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight shell"&gt;&lt;code&gt;lscpu
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;





&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight shell"&gt;&lt;code&gt;hwloc-ls
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;The &lt;code&gt;hwloc&lt;/code&gt; package is especially useful for visualizing CPU topology and NUMA layout.&lt;/p&gt;




&lt;h2&gt;
  
  
  Best Practices in HPC
&lt;/h2&gt;

&lt;h3&gt;
  
  
  1. Use Scheduler Managed Affinity
&lt;/h3&gt;

&lt;p&gt;Let the cluster scheduler manage CPU placement whenever possible.&lt;/p&gt;

&lt;p&gt;For example:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight shell"&gt;&lt;code&gt;&lt;span class="c"&gt;#SBATCH --cpus-per-task=8&lt;/span&gt;
&lt;span class="c"&gt;#SBATCH --cpu-bind=cores&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;






&lt;h3&gt;
  
  
  2. Keep MPI Ranks NUMA Aware
&lt;/h3&gt;

&lt;p&gt;Try to keep MPI ranks and memory allocations within the same NUMA domain.&lt;/p&gt;

&lt;p&gt;Tools like &lt;code&gt;numactl&lt;/code&gt; can help.&lt;/p&gt;




&lt;h3&gt;
  
  
  3. Benchmark Different Configurations
&lt;/h3&gt;

&lt;p&gt;Different applications behave differently.&lt;/p&gt;

&lt;p&gt;Always test:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Core binding&lt;/li&gt;
&lt;li&gt;Socket binding&lt;/li&gt;
&lt;li&gt;NUMA placement&lt;/li&gt;
&lt;li&gt;Hyperthreading enabled vs disabled&lt;/li&gt;
&lt;/ul&gt;




&lt;h3&gt;
  
  
  4. Monitor CPU Migrations
&lt;/h3&gt;

&lt;p&gt;High CPU migrations can indicate poor affinity configuration.&lt;/p&gt;

&lt;p&gt;Useful commands:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight shell"&gt;&lt;code&gt;pidstat &lt;span class="nt"&gt;-w&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;





&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight shell"&gt;&lt;code&gt;perf &lt;span class="nb"&gt;stat&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;






&lt;h2&gt;
  
  
  Final Thoughts
&lt;/h2&gt;

&lt;p&gt;CPU pinning and affinity are often overlooked in HPC environments, but they directly affect application scalability and runtime consistency.&lt;/p&gt;

&lt;p&gt;Two jobs using the same resources can perform very differently simply because of process placement. Understanding CPU topology, NUMA behavior, and scheduler affinity policies is essential for getting the best performance from modern HPC clusters.&lt;/p&gt;

&lt;p&gt;In many cases, properly placing and pinning processes to CPU cores can improve performance without upgrading the hardware.&lt;/p&gt;

</description>
      <category>ai</category>
      <category>productivity</category>
      <category>hpc</category>
      <category>slurm</category>
    </item>
    <item>
      <title>How Slurm Handles Resource Allocation Internally</title>
      <dc:creator>Muhammad Zubair Bin Akbar</dc:creator>
      <pubDate>Wed, 13 May 2026 19:05:33 +0000</pubDate>
      <link>https://dev.to/zubairakbar/how-slurm-handles-resource-allocation-internally-3fj5</link>
      <guid>https://dev.to/zubairakbar/how-slurm-handles-resource-allocation-internally-3fj5</guid>
      <description>&lt;p&gt;If you work with HPC clusters, chances are you use slurm every day to submit jobs, monitor queues, and manage compute resources.&lt;/p&gt;

&lt;p&gt;Most users know commands like sbatch, squeue, and sinfo, but fewer understand what actually happens internally when a job is submitted.&lt;/p&gt;

&lt;p&gt;This article explains how Slurm handles resource allocation behind the scenes, from job submission to execution on compute nodes.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  What Happens When You Submit a Job?
&lt;/h2&gt;

&lt;p&gt;When a user runs:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight shell"&gt;&lt;code&gt;sbatch job.sh
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;Slurm begins a multi step workflow internally.&lt;/p&gt;

&lt;h3&gt;
  
  
  The main components involved are:
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;slurmctld → Central controller daemon&lt;/li&gt;
&lt;li&gt;slurmd → Compute node daemon&lt;/li&gt;
&lt;li&gt;slurmdbd → Accounting database daemon (optional but common)&lt;/li&gt;
&lt;li&gt;Scheduler plugin&lt;/li&gt;
&lt;li&gt;Select plugin&lt;/li&gt;
&lt;li&gt;Cgroups/task plugins&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Each component has a specific role in resource allocation.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  Step 1: Job Submission
&lt;/h2&gt;

&lt;p&gt;The sbatch command sends the job request to slurmctld.&lt;/p&gt;

&lt;h3&gt;
  
  
  The request includes:
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;Number of nodes&lt;/li&gt;
&lt;li&gt;CPUs&lt;/li&gt;
&lt;li&gt;Memory&lt;/li&gt;
&lt;li&gt;GPUs&lt;/li&gt;
&lt;li&gt;Time limit&lt;/li&gt;
&lt;li&gt;Partition&lt;/li&gt;
&lt;li&gt;Constraints&lt;/li&gt;
&lt;li&gt;QoS&lt;/li&gt;
&lt;li&gt;Account information&lt;/li&gt;
&lt;/ul&gt;

&lt;h3&gt;
  
  
  Example:
&lt;/h3&gt;



&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight shell"&gt;&lt;code&gt;&lt;span class="c"&gt;#SBATCH --nodes=2&lt;/span&gt;
&lt;span class="c"&gt;#SBATCH --ntasks-per-node=32&lt;/span&gt;
&lt;span class="c"&gt;#SBATCH --mem=128G&lt;/span&gt;
&lt;span class="c"&gt;#SBATCH --time=04:00:00&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;At this stage, Slurm creates a job record and places it into the pending queue.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  Step 2: Job Validation
&lt;/h2&gt;

&lt;p&gt;Before scheduling the job, Slurm validates several things internally.&lt;/p&gt;

&lt;h3&gt;
  
  
  User &amp;amp; Account Checks
&lt;/h3&gt;

&lt;p&gt;Slurm verifies:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;User permissions&lt;/li&gt;
&lt;li&gt;Account associations&lt;/li&gt;
&lt;li&gt;QoS limits&lt;/li&gt;
&lt;li&gt;Fairshare policies&lt;/li&gt;
&lt;li&gt;Partition access&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;If accounting is enabled, slurmdbd provides usage statistics and limits.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  Step 3: Scheduler Evaluation
&lt;/h2&gt;

&lt;p&gt;Now the scheduler starts evaluating the job.&lt;/p&gt;

&lt;p&gt;The default scheduler in Slurm is:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;sched/backfill
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;This scheduler performs two important tasks:&lt;/p&gt;

&lt;p&gt;Main Scheduling Pass&lt;/p&gt;

&lt;h3&gt;
  
  
  It checks:
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;Available resources&lt;/li&gt;
&lt;li&gt;Job priority&lt;/li&gt;
&lt;li&gt;Node states&lt;/li&gt;
&lt;li&gt;Reservations&lt;/li&gt;
&lt;li&gt;Limits&lt;/li&gt;
&lt;/ul&gt;

&lt;h3&gt;
  
  
  Backfill Scheduling
&lt;/h3&gt;

&lt;p&gt;Backfill allows smaller jobs to run without delaying higher priority jobs.&lt;/p&gt;

&lt;p&gt;This improves overall cluster utilization.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  How Job Priority Is Calculated
&lt;/h2&gt;

&lt;p&gt;Slurm calculates a dynamic priority score.&lt;/p&gt;

&lt;h3&gt;
  
  
  Factors include:
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;Fairshare usage&lt;/li&gt;
&lt;li&gt;Job age&lt;/li&gt;
&lt;li&gt;Job size&lt;/li&gt;
&lt;li&gt;Partition priority&lt;/li&gt;
&lt;li&gt;QoS priority&lt;/li&gt;
&lt;li&gt;Association priority&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Internally, the priority plugin combines these values into a single score.&lt;/p&gt;

&lt;h3&gt;
  
  
  Example:
&lt;/h3&gt;

&lt;p&gt;&lt;code&gt;Priority = Age + Fairshare + JobSize + Partition + QoS&lt;/code&gt;&lt;/p&gt;

&lt;p&gt;Higher score means earlier scheduling.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  Step 4: Resource Selection
&lt;/h2&gt;

&lt;p&gt;Once the scheduler decides to run the job, Slurm uses the select plugin.&lt;/p&gt;

&lt;h3&gt;
  
  
  Most clusters use:
&lt;/h3&gt;



&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;select/cons_tres
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;This plugin handles consumable resources using TRES.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  What Are TRES?
&lt;/h2&gt;

&lt;p&gt;TRES stands for:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;Trackable RESources
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h3&gt;
  
  
  Examples:
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;CPU&lt;/li&gt;
&lt;li&gt;Memory&lt;/li&gt;
&lt;li&gt;GPU&lt;/li&gt;
&lt;li&gt;Node&lt;/li&gt;
&lt;li&gt;License&lt;/li&gt;
&lt;li&gt;Burst buffer&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;This model allows Slurm to track resources very precisely.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  Internal Node Selection
&lt;/h2&gt;

&lt;h3&gt;
  
  
  The select plugin now determines:
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;Which nodes are eligible&lt;/li&gt;
&lt;li&gt;How CPUs are distributed&lt;/li&gt;
&lt;li&gt;Memory allocation&lt;/li&gt;
&lt;li&gt;GPU placement&lt;/li&gt;
&lt;li&gt;Socket/core binding&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Slurm checks node topology information stored in memory by slurmctld.&lt;/p&gt;

&lt;h2&gt;
  
  
  Example:
&lt;/h2&gt;



&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight yaml"&gt;&lt;code&gt;&lt;span class="na"&gt;NodeA&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
  &lt;span class="s"&gt;64 CPUs&lt;/span&gt;
  &lt;span class="s"&gt;512 GB RAM&lt;/span&gt;
  &lt;span class="s"&gt;4 GPUs&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h3&gt;
  
  
  If the job requests:
&lt;/h3&gt;



&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;32 CPUs + 2 GPUs
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;Slurm reserves exactly those resources internally.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  Step 5: Resource Reservation
&lt;/h2&gt;

&lt;p&gt;After node selection, Slurm marks resources as allocated.&lt;/p&gt;

&lt;h3&gt;
  
  
  Internally:
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;CPUs become unavailable to other jobs&lt;/li&gt;
&lt;li&gt;Memory counters are reduced&lt;/li&gt;
&lt;li&gt;GPUs are reserved&lt;/li&gt;
&lt;li&gt;Node state changes&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;You can observe this using:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight shell"&gt;&lt;code&gt;scontrol show node
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;or&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight shell"&gt;&lt;code&gt;squeue
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  Step 6: Launching the Job
&lt;/h2&gt;

&lt;p&gt;Now slurmctld contacts the slurmd daemon on allocated nodes.&lt;/p&gt;

&lt;h3&gt;
  
  
  The compute node daemon performs:
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;Environment setup&lt;/li&gt;
&lt;li&gt;UID/GID validation&lt;/li&gt;
&lt;li&gt;Cgroup creation&lt;/li&gt;
&lt;li&gt;CPU binding&lt;/li&gt;
&lt;li&gt;Memory enforcement&lt;/li&gt;
&lt;li&gt;Task launching&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  How Cgroups Enforce Limits
&lt;/h2&gt;

&lt;p&gt;Modern Slurm clusters heavily rely on Linux cgroups.&lt;/p&gt;

&lt;p&gt;Cgroups ensure a job cannot exceed allocated resources.&lt;/p&gt;

&lt;p&gt;Examples:&lt;/p&gt;

&lt;h3&gt;
  
  
  CPU Enforcement
&lt;/h3&gt;

&lt;p&gt;Only allocated CPU cores are accessible&lt;/p&gt;

&lt;h3&gt;
  
  
  Memory Enforcement
&lt;/h3&gt;

&lt;p&gt;Memory usage beyond limit triggers OOM kill&lt;/p&gt;

&lt;h3&gt;
  
  
  GPU Isolation
&lt;/h3&gt;

&lt;p&gt;Only assigned GPUs are visible&lt;/p&gt;

&lt;p&gt;This is why users see:&lt;/p&gt;

&lt;p&gt;&lt;code&gt;CUDA_VISIBLE_DEVICES=0&lt;/code&gt;&lt;/p&gt;

&lt;p&gt;automatically set inside jobs.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  CPU Binding and Affinity
&lt;/h2&gt;

&lt;p&gt;Slurm also handles CPU affinity internally.&lt;/p&gt;

&lt;h3&gt;
  
  
  This improves:
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;NUMA locality&lt;/li&gt;
&lt;li&gt;Cache efficiency&lt;/li&gt;
&lt;li&gt;MPI performance&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Example:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight shell"&gt;&lt;code&gt;srun &lt;span class="nt"&gt;--cpu-bind&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;cores
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;Internally, Slurm maps tasks to specific CPU cores using topology-aware scheduling.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  Step 7: Job Execution
&lt;/h2&gt;

&lt;p&gt;Once everything is configured:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Processes start&lt;/li&gt;
&lt;li&gt;Accounting begins&lt;/li&gt;
&lt;li&gt;Usage metrics are collected&lt;/li&gt;
&lt;/ul&gt;

&lt;h3&gt;
  
  
  Slurm tracks:
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;CPU time&lt;/li&gt;
&lt;li&gt;Memory usage&lt;/li&gt;
&lt;li&gt;GPU usage&lt;/li&gt;
&lt;li&gt;Energy consumption&lt;/li&gt;
&lt;li&gt;Exit codes&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;These statistics are later visible through:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight shell"&gt;&lt;code&gt;sacct
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  What Happens When the Job Finishes?
&lt;/h2&gt;

&lt;h3&gt;
  
  
  After completion:
&lt;/h3&gt;

&lt;ol&gt;
&lt;li&gt;Resources are released&lt;/li&gt;
&lt;li&gt;Node state is updated&lt;/li&gt;
&lt;li&gt;Accounting data is stored&lt;/li&gt;
&lt;li&gt;Scheduler reevaluates pending jobs&lt;/li&gt;
&lt;/ol&gt;

&lt;p&gt;The released resources immediately become available for new allocations.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  Why Understanding This Matters
&lt;/h2&gt;

&lt;p&gt;Knowing how Slurm allocates resources helps administrators and users:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Troubleshoot pending jobs&lt;/li&gt;
&lt;li&gt;Optimize scheduling&lt;/li&gt;
&lt;li&gt;Improve cluster utilization&lt;/li&gt;
&lt;li&gt;Diagnose CPU or memory contention&lt;/li&gt;
&lt;li&gt;Tune fairshare policies&lt;/li&gt;
&lt;li&gt;Understand performance bottlenecks&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;It also makes debugging much easier when dealing with issues like:&lt;/p&gt;

&lt;p&gt;&lt;code&gt;ReqNodeNotAvail&lt;br&gt;
Resources&lt;br&gt;
Priority&lt;br&gt;
QOSMaxCpuPerUserLimit&lt;/code&gt;&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  Final Thoughts
&lt;/h2&gt;

&lt;p&gt;Slurm does much more than simply queue jobs.&lt;/p&gt;

&lt;h3&gt;
  
  
  Internally, it performs:
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;Policy validation&lt;/li&gt;
&lt;li&gt;Priority calculations&lt;/li&gt;
&lt;li&gt;Topology aware scheduling&lt;/li&gt;
&lt;li&gt;Precise resource accounting&lt;/li&gt;
&lt;li&gt;Cgroup enforcement&lt;/li&gt;
&lt;li&gt;Distributed task launching&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Understanding these internals gives HPC administrators better control over cluster performance and helps users write more efficient jobs.&lt;/p&gt;

&lt;p&gt;The next time you run sbatch, remember that an entire scheduling engine is working behind the scenes to decide exactly where and how your workload should run.&lt;/p&gt;

</description>
      <category>ai</category>
      <category>hpc</category>
      <category>slurm</category>
      <category>productivity</category>
    </item>
    <item>
      <title>InfiniBand vs Omni Path vs Ethernet for AI Workloads</title>
      <dc:creator>Muhammad Zubair Bin Akbar</dc:creator>
      <pubDate>Mon, 11 May 2026 19:27:00 +0000</pubDate>
      <link>https://dev.to/zubairakbar/infiniband-vs-omni-path-vs-ethernet-for-ai-workloads-55dh</link>
      <guid>https://dev.to/zubairakbar/infiniband-vs-omni-path-vs-ethernet-for-ai-workloads-55dh</guid>
      <description>&lt;p&gt;AI workloads are pushing HPC and data center networks harder than ever. Training large language models, distributed deep learning, and high speed data pipelines depend heavily on fast interconnects between compute nodes.&lt;/p&gt;

&lt;p&gt;When GPUs spend more time waiting for data than processing it, the network becomes the bottleneck.&lt;/p&gt;

&lt;p&gt;Three major networking technologies are commonly discussed in AI and HPC environments:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;InfiniBand&lt;/li&gt;
&lt;li&gt;Intel Omni Path&lt;/li&gt;
&lt;li&gt;Ethernet&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Each comes with different strengths, trade offs, and real world use cases.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  Why Network Fabric Matters in AI
&lt;/h2&gt;

&lt;p&gt;Modern AI training is rarely limited to a single GPU or node.&lt;/p&gt;

&lt;h3&gt;
  
  
  Distributed frameworks like:
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;PyTorch DDP&lt;/li&gt;
&lt;li&gt;DeepSpeed&lt;/li&gt;
&lt;li&gt;Horovod&lt;/li&gt;
&lt;li&gt;TensorFlow Distributed&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;constantly exchange gradients, parameters, and synchronization data between nodes.&lt;/p&gt;

&lt;p&gt;The faster this communication happens, the better the training performance scales.&lt;/p&gt;

&lt;h3&gt;
  
  
  Key factors include:
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;Latency&lt;/li&gt;
&lt;li&gt;Bandwidth&lt;/li&gt;
&lt;li&gt;RDMA support&lt;/li&gt;
&lt;li&gt;Scalability&lt;/li&gt;
&lt;li&gt;Congestion handling&lt;/li&gt;
&lt;li&gt;GPU communication efficiency&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  1. InfiniBand
&lt;/h2&gt;

&lt;p&gt;NVIDIA InfiniBand is considered the gold standard for high performance AI and HPC clusters.&lt;/p&gt;

&lt;p&gt;It is designed specifically for ultra low latency and extremely high throughput communication.&lt;/p&gt;

&lt;h3&gt;
  
  
  Key Features
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;RDMA (Remote Direct Memory Access)&lt;/li&gt;
&lt;li&gt;GPUDirect RDMA support&lt;/li&gt;
&lt;li&gt;Very low latency&lt;/li&gt;
&lt;li&gt;High bandwidth (HDR, NDR generations)&lt;/li&gt;
&lt;li&gt;Adaptive routing&lt;/li&gt;
&lt;li&gt;Lossless communication&lt;/li&gt;
&lt;/ul&gt;

&lt;h3&gt;
  
  
  Why AI Clusters Love InfiniBand
&lt;/h3&gt;

&lt;p&gt;Large AI workloads generate massive all reduce traffic between GPUs.&lt;/p&gt;

&lt;p&gt;InfiniBand performs exceptionally well because it minimizes CPU involvement and allows direct GPU to GPU communication across nodes.&lt;/p&gt;

&lt;h3&gt;
  
  
  This improves:
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;Multi node GPU scaling&lt;/li&gt;
&lt;li&gt;Training efficiency&lt;/li&gt;
&lt;li&gt;Synchronization speed&lt;/li&gt;
&lt;li&gt;Cluster utilization&lt;/li&gt;
&lt;/ul&gt;

&lt;h3&gt;
  
  
  Common Use Cases
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;Large scale LLM training&lt;/li&gt;
&lt;li&gt;HPC supercomputers&lt;/li&gt;
&lt;li&gt;GPU heavy AI clusters&lt;/li&gt;
&lt;li&gt;Research environments&lt;/li&gt;
&lt;/ul&gt;

&lt;h3&gt;
  
  
  Limitations
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;Expensive hardware&lt;/li&gt;
&lt;li&gt;Complex deployment&lt;/li&gt;
&lt;li&gt;Specialized networking expertise required&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  2. Omni Path
&lt;/h2&gt;

&lt;p&gt;Intel Omni Path was Intel’s answer to InfiniBand for HPC environments.&lt;/p&gt;

&lt;p&gt;It focused on delivering high throughput with strong scalability at a potentially lower cost.&lt;/p&gt;

&lt;h3&gt;
  
  
  Key Features
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;Low latency fabric&lt;/li&gt;
&lt;li&gt;High port density&lt;/li&gt;
&lt;li&gt;Efficient MPI communication&lt;/li&gt;
&lt;li&gt;Good scalability for HPC workloads&lt;/li&gt;
&lt;/ul&gt;

&lt;h3&gt;
  
  
  Strengths
&lt;/h3&gt;

&lt;p&gt;Omni Path performed well in:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;MPI based HPC clusters&lt;/li&gt;
&lt;li&gt;Scientific simulations&lt;/li&gt;
&lt;li&gt;CPU centric workloads&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;It also reduced switch complexity in some deployments due to its architecture.&lt;/p&gt;

&lt;h3&gt;
  
  
  Challenges for AI Workloads
&lt;/h3&gt;

&lt;p&gt;While Omni Path worked well for traditional HPC, it struggled to gain traction in GPU dominated AI ecosystems.&lt;/p&gt;

&lt;h3&gt;
  
  
  Reasons included:
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;Limited GPU ecosystem support&lt;/li&gt;
&lt;li&gt;Less mature GPUDirect integration&lt;/li&gt;
&lt;li&gt;Smaller vendor ecosystem&lt;/li&gt;
&lt;li&gt;Reduced industry adoption over time&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Today, most modern AI deployments lean toward InfiniBand or high speed Ethernet instead.&lt;/p&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  3. Ethernet
&lt;/h2&gt;

&lt;p&gt;Broadcom and other vendors continue pushing Ethernet into AI networking with higher speeds like:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;100GbE&lt;/li&gt;
&lt;li&gt;200GbE&lt;/li&gt;
&lt;li&gt;400GbE&lt;/li&gt;
&lt;li&gt;800GbE&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Ethernet remains the most widely deployed networking technology globally.&lt;/p&gt;

&lt;h3&gt;
  
  
  Key Features
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;Easy integration&lt;/li&gt;
&lt;li&gt;Lower cost&lt;/li&gt;
&lt;li&gt;Massive ecosystem support&lt;/li&gt;
&lt;li&gt;Simpler operations&lt;/li&gt;
&lt;li&gt;Familiar tooling&lt;/li&gt;
&lt;/ul&gt;

&lt;h3&gt;
  
  
  Ethernet in Modern AI
&lt;/h3&gt;

&lt;p&gt;Traditional Ethernet had higher latency compared to InfiniBand, but newer technologies have improved performance significantly.&lt;/p&gt;

&lt;h3&gt;
  
  
  Examples include:
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;RoCE (RDMA over Converged Ethernet)&lt;/li&gt;
&lt;li&gt;SmartNICs&lt;/li&gt;
&lt;li&gt;DPU acceleration&lt;/li&gt;
&lt;li&gt;Lossless Ethernet configurations&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Many organizations now run AI workloads successfully on high speed Ethernet fabrics.&lt;/p&gt;

&lt;h3&gt;
  
  
  Strengths
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;Cost effective scaling&lt;/li&gt;
&lt;li&gt;Easier maintenance&lt;/li&gt;
&lt;li&gt;Better compatibility with enterprise environments&lt;/li&gt;
&lt;li&gt;Flexible vendor choices&lt;/li&gt;
&lt;/ul&gt;

&lt;h3&gt;
  
  
  Weaknesses
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;Usually higher latency than InfiniBand&lt;/li&gt;
&lt;li&gt;Congestion tuning can become complex&lt;/li&gt;
&lt;li&gt;RoCE requires careful configuration&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  Which One Should You Choose?
&lt;/h2&gt;

&lt;h3&gt;
  
  
  Choose InfiniBand if:
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;You train large AI models&lt;/li&gt;
&lt;li&gt;You run multi node GPU clusters&lt;/li&gt;
&lt;li&gt;Maximum performance matters&lt;/li&gt;
&lt;li&gt;Budget is less of a concern&lt;/li&gt;
&lt;/ul&gt;

&lt;h3&gt;
  
  
  Choose Omni Path if:
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;You already operate Intel HPC infrastructure&lt;/li&gt;
&lt;li&gt;Your workloads are MPI heavy&lt;/li&gt;
&lt;li&gt;GPU scaling is not the main priority&lt;/li&gt;
&lt;/ul&gt;

&lt;h3&gt;
  
  
  Choose Ethernet if:
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;You want operational simplicity&lt;/li&gt;
&lt;li&gt;You need enterprise compatibility&lt;/li&gt;
&lt;li&gt;Budget matters&lt;/li&gt;
&lt;li&gt;Your AI workloads are medium scale&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;⸻&lt;/p&gt;

&lt;h2&gt;
  
  
  Final Thoughts
&lt;/h2&gt;

&lt;p&gt;There is no universal winner.&lt;/p&gt;

&lt;h3&gt;
  
  
  The right interconnect depends on:
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;Workload type&lt;/li&gt;
&lt;li&gt;Cluster scale&lt;/li&gt;
&lt;li&gt;Budget&lt;/li&gt;
&lt;li&gt;GPU usage&lt;/li&gt;
&lt;li&gt;Operational expertise&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;For cutting edge AI training, InfiniBand still dominates performance focused deployments.&lt;/p&gt;

&lt;p&gt;For enterprise AI environments, Ethernet continues evolving rapidly and closing the gap.&lt;/p&gt;

&lt;p&gt;Omni Path played an important role in HPC networking, but its presence in modern AI infrastructure has become much smaller compared to InfiniBand and Ethernet.&lt;/p&gt;

&lt;p&gt;As AI clusters continue growing, networking decisions are becoming just as important as CPU and GPU selection.&lt;/p&gt;

</description>
      <category>ai</category>
      <category>networking</category>
      <category>hpc</category>
      <category>productivity</category>
    </item>
    <item>
      <title>How HPC Clusters Accelerate AI/ML Training</title>
      <dc:creator>Muhammad Zubair Bin Akbar</dc:creator>
      <pubDate>Sat, 09 May 2026 21:36:44 +0000</pubDate>
      <link>https://dev.to/zubairakbar/how-hpc-clusters-accelerate-aiml-training-15a2</link>
      <guid>https://dev.to/zubairakbar/how-hpc-clusters-accelerate-aiml-training-15a2</guid>
      <description>&lt;p&gt;Artificial Intelligence and Machine Learning are growing faster than ever. From large language models to computer vision and scientific simulations, modern AI workloads require massive computing power.&lt;/p&gt;

&lt;p&gt;Training a model on a normal workstation can take days, weeks, or even months. This is where High Performance Computing, also known as HPC, becomes extremely valuable.&lt;/p&gt;

&lt;p&gt;An HPC cluster allows researchers, engineers, startups, and enterprises to train AI models faster, process larger datasets, and scale workloads efficiently.&lt;/p&gt;

&lt;h2&gt;
  
  
  What is an HPC Cluster?
&lt;/h2&gt;

&lt;p&gt;An HPC cluster is a group of interconnected servers working together as a single powerful computing environment.&lt;/p&gt;

&lt;h3&gt;
  
  
  These clusters usually contain:
&lt;/h3&gt;

&lt;ol&gt;
&lt;li&gt;Multiple compute nodes
&lt;/li&gt;
&lt;li&gt;High core count CPUs
&lt;/li&gt;
&lt;li&gt;Powerful GPUs
&lt;/li&gt;
&lt;li&gt;High speed networking
&lt;/li&gt;
&lt;li&gt;Parallel storage systems
&lt;/li&gt;
&lt;li&gt;Job scheduling software like Slurm
&lt;/li&gt;
&lt;/ol&gt;

&lt;p&gt;Instead of relying on a single machine, workloads are distributed across many systems.&lt;/p&gt;

&lt;h2&gt;
  
  
  Why AI and ML Need HPC
&lt;/h2&gt;

&lt;p&gt;Modern AI training involves billions of calculations. Large datasets and deep neural networks demand huge computational resources.&lt;/p&gt;

&lt;h3&gt;
  
  
  Without HPC infrastructure, organizations often face:
&lt;/h3&gt;

&lt;ol&gt;
&lt;li&gt;Slow training times
&lt;/li&gt;
&lt;li&gt;GPU bottlenecks
&lt;/li&gt;
&lt;li&gt;Memory limitations
&lt;/li&gt;
&lt;li&gt;Storage performance issues
&lt;/li&gt;
&lt;li&gt;Scaling challenges
&lt;/li&gt;
&lt;/ol&gt;

&lt;p&gt;HPC solves these problems by providing distributed computing and parallel execution.&lt;/p&gt;

&lt;h2&gt;
  
  
  Faster Model Training
&lt;/h2&gt;

&lt;p&gt;One of the biggest advantages of HPC is reduced training time.&lt;/p&gt;

&lt;p&gt;For example, training a deep learning model on a single GPU may take several days. Using an HPC cluster with multiple GPUs across several nodes can reduce this time dramatically.&lt;/p&gt;

&lt;h3&gt;
  
  
  Frameworks such as:
&lt;/h3&gt;

&lt;ol&gt;
&lt;li&gt;PyTorch
&lt;/li&gt;
&lt;li&gt;TensorFlow
&lt;/li&gt;
&lt;li&gt;Horovod
&lt;/li&gt;
&lt;li&gt;DeepSpeed
&lt;/li&gt;
&lt;/ol&gt;

&lt;p&gt;can distribute training across many GPUs simultaneously.&lt;/p&gt;

&lt;p&gt;This allows data parallelism and model parallelism at scale.&lt;/p&gt;

&lt;h2&gt;
  
  
  Efficient GPU Utilization
&lt;/h2&gt;

&lt;p&gt;GPUs are expensive resources. HPC clusters help maximize GPU usage efficiently.&lt;/p&gt;

&lt;h3&gt;
  
  
  Schedulers like Slurm can:
&lt;/h3&gt;

&lt;ol&gt;
&lt;li&gt;Allocate GPUs dynamically
&lt;/li&gt;
&lt;li&gt;Queue workloads efficiently
&lt;/li&gt;
&lt;li&gt;Prevent resource conflicts
&lt;/li&gt;
&lt;li&gt;Improve overall cluster utilization
&lt;/li&gt;
&lt;/ol&gt;

&lt;p&gt;This ensures that GPUs remain productive instead of sitting idle.&lt;/p&gt;

&lt;h2&gt;
  
  
  Scalability for Large Datasets
&lt;/h2&gt;

&lt;p&gt;AI models continue to grow in size. Datasets now reach terabytes or even petabytes.&lt;/p&gt;

&lt;h3&gt;
  
  
  HPC clusters provide scalable storage systems such as:
&lt;/h3&gt;

&lt;ol&gt;
&lt;li&gt;Lustre
&lt;/li&gt;
&lt;li&gt;BeeGFS
&lt;/li&gt;
&lt;li&gt;GPFS
&lt;/li&gt;
&lt;/ol&gt;

&lt;p&gt;These parallel file systems allow high speed data access from multiple nodes at the same time.&lt;/p&gt;

&lt;p&gt;As a result, training pipelines become faster and more reliable.&lt;/p&gt;

&lt;h2&gt;
  
  
  Distributed Training Made Easier
&lt;/h2&gt;

&lt;p&gt;Modern AI frameworks are designed to work well with HPC environments.&lt;/p&gt;

&lt;h3&gt;
  
  
  Using technologies like:
&lt;/h3&gt;

&lt;ol&gt;
&lt;li&gt;NCCL
&lt;/li&gt;
&lt;li&gt;MPI
&lt;/li&gt;
&lt;li&gt;RDMA
&lt;/li&gt;
&lt;li&gt;Omni Path or InfiniBand networking
&lt;/li&gt;
&lt;/ol&gt;

&lt;p&gt;clusters can achieve low latency communication between GPUs and compute nodes.&lt;/p&gt;

&lt;p&gt;This becomes critical when training large transformer models or running multi GPU workloads.&lt;/p&gt;

&lt;h2&gt;
  
  
  Better Resource Sharing
&lt;/h2&gt;

&lt;p&gt;HPC clusters are ideal for universities, research labs, and enterprises where many users need access to computing resources.&lt;/p&gt;

&lt;p&gt;Instead of every team purchasing separate hardware, a centralized HPC environment allows shared access to:&lt;/p&gt;

&lt;ol&gt;
&lt;li&gt;GPUs
&lt;/li&gt;
&lt;li&gt;CPUs
&lt;/li&gt;
&lt;li&gt;Memory
&lt;/li&gt;
&lt;li&gt;Storage
&lt;/li&gt;
&lt;li&gt;Software environments
&lt;/li&gt;
&lt;/ol&gt;

&lt;p&gt;This reduces cost and improves operational efficiency.&lt;/p&gt;

&lt;h2&gt;
  
  
  AI Use Cases That Benefit from HPC
&lt;/h2&gt;

&lt;h3&gt;
  
  
  HPC clusters are widely used for:
&lt;/h3&gt;

&lt;ol&gt;
&lt;li&gt;Large Language Models
&lt;/li&gt;
&lt;li&gt;Computer Vision
&lt;/li&gt;
&lt;li&gt;Medical Imaging
&lt;/li&gt;
&lt;li&gt;Weather Prediction
&lt;/li&gt;
&lt;li&gt;Drug Discovery
&lt;/li&gt;
&lt;li&gt;Financial Modeling
&lt;/li&gt;
&lt;li&gt;Autonomous Vehicle Research
&lt;/li&gt;
&lt;li&gt;Scientific Simulations
&lt;/li&gt;
&lt;/ol&gt;

&lt;p&gt;Many of these workloads are impossible to run efficiently on a single machine.&lt;/p&gt;

&lt;h2&gt;
  
  
  Challenges to Consider
&lt;/h2&gt;

&lt;p&gt;Although HPC offers major advantages, there are still challenges:&lt;/p&gt;

&lt;ol&gt;
&lt;li&gt;Infrastructure cost
&lt;/li&gt;
&lt;li&gt;Power and cooling requirements
&lt;/li&gt;
&lt;li&gt;GPU availability
&lt;/li&gt;
&lt;li&gt;Network complexity
&lt;/li&gt;
&lt;li&gt;Cluster management
&lt;/li&gt;
&lt;li&gt;Software compatibility
&lt;/li&gt;
&lt;/ol&gt;

&lt;p&gt;However, the long term performance gains usually outweigh the initial setup effort.&lt;/p&gt;

&lt;h2&gt;
  
  
  Final Thoughts
&lt;/h2&gt;

&lt;p&gt;AI and Machine Learning workloads are becoming increasingly demanding. Traditional systems are often not enough to handle modern training requirements.&lt;/p&gt;

&lt;p&gt;HPC clusters provide the computing power, scalability, and efficiency needed for advanced AI development.&lt;/p&gt;

&lt;p&gt;Whether you are training deep learning models, processing massive datasets, or running distributed workloads, HPC can significantly accelerate your AI journey.&lt;/p&gt;

&lt;p&gt;As AI continues to evolve, HPC infrastructure will become even more important for research and innovation.&lt;/p&gt;

</description>
      <category>ai</category>
      <category>machinelearning</category>
      <category>highperformancecomputing</category>
      <category>productivity</category>
    </item>
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