Function profileSystem

scripts/profiler/main.ts:384–450

(
  scenario: Scenario,
  resolved: ResolvedCommand,
  runDir: string,
  baseEnv: NodeJS.ProcessEnv,
  args: ProfileArgs,
)

}

function profileSystem(
  scenario: Scenario,
  resolved: ResolvedCommand,
  runDir: string,
  baseEnv: NodeJS.ProcessEnv,
  args: ProfileArgs,
): RunRecord {
  const perfData = path.join(runDir, "perf.data");
  const wrapped = wrapWithPerfCpu(
    resolved.command,
    perfData,
    args.sampleRateHz,
  );

  const env: NodeJS.ProcessEnv = {
    ...baseEnv,
    NODE_OPTIONS: mergeNodeOptions(baseEnv.NODE_OPTIONS, PERF_JS_NODE_OPTIONS),
  };

  logStep(`[${scenario.id}] system profile: ${resolved.command}`);
  const record = runInScenario(
    wrapped,
    scenario,
    env,
    commandLogPath(runDir, Mode.System),
    args.showOutput,
  );

  // Resolving JS frame names depends on the /tmp/perf-<pid>.map files the
  // profiled processes just wrote. Symbolize to ensure output is
  // self-contained.
  const samples = path.join(runDir, PERF_SCRIPT_OUTPUT_FILENAME);

  // Remove artifacts from a previous run in the same --out-dir, so that a
  // crash between symbolizing and compressing does not leave stale samples
  // behind.
  rmSync(`${samples}.gz`, { force: true });

  const symbolized = runPostProcess(
    `perf script -i ${shellQuote(perfData)} > ${shellQuote(samples)}`,
  );

  runPostProcess(
    `perf report -i ${shellQuote(perfData)} --stdio --no-children --no-call-graph --sort dso > ${shellQuote(path.join(runDir, "dso.txt"))}`,
  );
  runPostProcess(
    `perf report -i ${shellQuote(perfData)} --stdio --no-children --no-call-graph --sort dso,sym --percent-limit 0.05 > ${shellQuote(path.join(runDir, "report.txt"))}`,
  );

  if (symbolized) {
    runPostProcess(`gzip -f ${shellQuote(samples)}`);
  } else {
    // A truncated samples file would masquerade as a complete profile.
    rmSync(samples, { force: true });
  }

  // perf.data is machine-bound and large, so only keep it if the user
  // explicitly requested it or if symbolization failed