csperf Doctor: First Command to Diagnose Toolchain Issues

Why this lesson exists

When a csperf run fails, the default reaction is to blame the perf tool for a bad measurement. In reality, the culprit is often an incomplete or mis‑configured compiler toolchain. The csperf doctor command is designed to surface those hidden problems before you even start a benchmark.

Recap — where we are in the series

Episode 1: Why a Single ./a.out Time Misleads Your Performance Claims – single‑shot timings are unreliable.
Episode 2: Warm vs Cold: Why a Single Trial Misleads Performance Claims – warm‑up and repeat are essential.
Episode 3: Screenshots Aren’t Evidence: Use csperf for Real Performance Artifacts – metadata‑rich artifacts beat screenshots.
Episode 4: Comparing Across Machines: Why Metadata Matters in csperf – machine metadata enables honest cross‑machine comparison.
Episode 5: csperf: A Lightweight Observatory for Honest Performance Tracking – observatory commands give quick, reliable evidence of your compiler environment.

The misconception

Many developers assume that a failing csperf run indicates a problem with the perf tool or the benchmark code. In practice, the failure is almost always due to missing compiler components, incorrect paths, or mismatched versions that prevent the toolchain from building the test harness.

What problem csperf solves (this episode's slice)

csperf doctor performs a quick sanity check of the compiler toolchain and the csperf installation. It verifies that:

• The compiler binary (clang, gcc, etc.) is reachable and executable.
• The required LLVM/Clang libraries are present.
• The csperf Python package can import its dependencies.
• The environment variables used by csperf are set correctly.

If any of these checks fail, the output clearly indicates the missing piece, saving you from chasing perf‑related noise.

Mental model

Think of csperf doctor as a health checkup for your performance measurement stack. Just as a doctor checks vital signs before a physical exam, this command checks the health of your compiler environment before you run any benchmarks.

Lab: install and first commands

1. Ensure your virtual environment is activated:

   source /home/aitr/projects/CompilerSutraPerfTool/.venv/bin/activate

1. Run the basic doctor check:

   csperf doctor

1. If you see any missing components, install them with:

   csperf doctor --install

Lab: what we ran on this machine

The machine on which we ran the lab is a Ryzen 7 9700X 8‑core (16 threads) running Ubuntu 24.04. The relevant machine metadata is captured in csperf/machine.txt:

hostname=f4c59d864117
CPU(s): 16
On‑line CPU(s) list: 0‑15
Vendor ID: AuthenticAMD
Model name: AMD Ryzen 7 9700X 8‑Core Processor
CPU max MHz: 5582.3008
CPU min MHz: 605.3100
BogoMIPS: 7599.98

The csperf doctor command was executed from the same environment and produced a csperf/doctor.txt artifact.

Results (real numbers only)

All checks in csperf/doctor.txt returned [ok]. No errors were reported. The machine metadata shows 16 logical CPUs and a maximum frequency of 5.58 GHz, which matches the expected performance baseline for this workload.

How to read the artifacts

• csperf/machine.txt – contains the raw system information captured by csperf.
• csperf/file‑list.txt – lists all artifacts generated during the run.
• csperf/doctor.txt – lists each sanity check with its status. Lines beginning with [ok] indicate a passed check; [missing] or [error] flag a problem.

When you open doctor.txt, look for sections labeled Compiler, LLVM, csperf, and Environment. Each section will have a list of checks.

Common mistakes (teacher checklist)

1. Skipping the doctor check – always run csperf doctor before any benchmark.
2. Using the wrong virtual environment – ensure the csperf virtualenv is activated.
3. Missing system dependencies – e.g., libclang-dev on Debian/Ubuntu.
4. Incorrect PATH – the compiler binary must be in the PATH.
5. Out‑of‑date csperf – upgrade with pip install --upgrade csperf.

Try this next (homework)

Run csperf doctor on a different machine (e.g., a cloud instance) and compare the output to the local machine. Note any differences in the checks that pass or fail. Do this tonight — Episode 7 starts by assuming you did.

Closing

csperf doctor is a lightweight, zero‑cost way to catch toolchain issues before they masquerade as perf failures. By incorporating it into your workflow, you eliminate a common source of noise and make your performance claims truly honest.

The series so far

• Episode 1 – Why a Single ./a.out Time Misleads Your Performance Claims
• Episode 2 – Warm vs Cold: Why a Single Trial Misleads Performance Claims
• Episode 3 – Screenshots Aren’t Evidence: Use csperf for Real Performance Artifacts
• Episode 4 – Comparing Across Machines: Why Metadata Matters in csperf
• Episode 5 – csperf: A Lightweight Observatory for Honest Performance Tracking
• Episode 6 – csperf Doctor: First Command to Diagnose Toolchain Issues (this article)

Teaser

Remember how csperf’s observatory commands give quick evidence (Episode 5), and next we’ll dive into the 30‑second quickstart win (Episode 7).

Comments

[OCTYN]

i'd add one deliberately broken-toolchain run to the lesson. a page full of [ok] shows the happy path, but removing a dependency proves doctor can spot it and returns a non-zero exit. especially important if someone puts this before a benchmark in CI, where printed [missing] with exit 0 would still look green.