DEV Community: Jacob Hitze

Less is similar

Jacob Hitze — Wed, 11 Dec 2024 01:32:50 +0000

Confusion Clear-up

There was some confusion on the last post about fah6 and what that meant. I currently do devops/platform engineering/cloud engineering for my day job. One of the tenants I hold dear is to treat servers like “cattle not pets”. So even though I want to name the servers after all the characters in the Fifth Element, I won’t.

Here’s a current snapshot of VMs from Xen Orchestra.

I’m new to Xen, and it’s a lot to learn. I have found it neat to work a layer under where I do for my day job. Each VM is running Ubuntu 22.04. By the way, are you all interested in the specs of the servers? Let me know in the comments!

Back to the point(s)!

So, 20 CPUs PPD seems to be within the margin of error. I’ve checked in on this one a few times over the last few days to see if there were any outliers. Nope. Just chugging’ along.

Next experiment

I had some suggestions come in (thank you!) from some fellow folders and some HPC experts. It seems there are two experiments to do.

Turn off SMT
Lock VMs to one CPU socket.

Turning off SMT requires less googling, so I’m gonna start with that on fah6. I’ll save the Xen cli googling for next time.

Less is the same?

Jacob Hitze — Fri, 06 Dec 2024 02:18:17 +0000

Yesterday I set fah6 to finish up the second group of CPUs. In theory it is now using just one CPU socket’s worth of threads.

Over 24 hours it finished the WUs, and started fresh on just one group.

The PPD didn’t go down. On the f@h discord, it was brought up that the realistic upper limit of the CPU cores is 32. Luckily I have an exact replica of that server, already running 32 CPUs.

So on these 2socket, 40c, 80t machines, setting CPUs to 80 produces roughly the same PPD as setting it to 40 or 32. The next test is lowering the CPUs setting to 20, to match one socket’s actual core count.

Anti-Yank Straps

Jacob Hitze — Wed, 04 Dec 2024 22:55:55 +0000

Well, today I learned something minor, but cool.

Those little Velcro straps are supposed to hold the power cable in. Less likely to get an accidental yank this way!

Is this thing on?

Jacob Hitze — Wed, 04 Dec 2024 22:22:55 +0000

Trying out this dev posting thingy.