benchmark: conditionally use spawn with taskset for cpu pinning

thisalihassan · marco-ippolito · commit 7508d4873600 · 2024-05-03T08:30:28.000+02:00
This change enhances the benchmarking tool by conditionally using the, spawn method with taskset for CPU pinning, improving consistency of benchmark results across different environments. Fixes: #52233 PR-URL: #52253 Reviewed-By: Matteo Collina <matteo.collina@gmail.com> Reviewed-By: Raz Luvaton <rluvaton@gmail.com> Reviewed-By: Yagiz Nizipli <yagiz.nizipli@sentry.io>
diff --git a/benchmark/_cli.js b/benchmark/_cli.js
@@ -125,3 +125,24 @@ CLI.prototype.shouldSkip = function(scripts) {
 
   return skip;
 };
+
+/**
+ * Extracts the CPU core setting from the CLI arguments.
+ * @returns {string|null} The CPU core setting if found, otherwise null.
+ */
+CLI.prototype.getCpuCoreSetting = function() {
+  const cpuCoreSetting = this.optional.set.find((s) => s.startsWith('CPUSET='));
+  if (!cpuCoreSetting) return null;
+
+  const value = cpuCoreSetting.split('=')[1];
+  // Validate the CPUSET value to match patterns like "0", "0-2", "0,1,2", "0,2-4,6" or "0,0,1-2"
+  const isValid = /^(\d+(-\d+)?)(,\d+(-\d+)?)*$/.test(value);
+  if (!isValid) {
+    throw new Error(`
+        Invalid CPUSET format: "${value}". Please use a single core number (e.g., "0"), 
+        a range of cores (e.g., "0-3"), or a list of cores/ranges 
+        (e.g., "0,2,4" or "0-2,4").\n\n${this.usage}
+    `);
+  }
+  return value;
+};
diff --git a/benchmark/compare.js b/benchmark/compare.js
@@ -1,6 +1,6 @@
 'use strict';
 
-const { fork } = require('child_process');
+const { spawn, fork } = require('node:child_process');
 const { inspect } = require('util');
 const path = require('path');
 const CLI = require('./_cli.js');
@@ -24,6 +24,12 @@ const cli = new CLI(`usage: ./node compare.js [options] [--] <category> ...
                                 repeated)
   --set      variable=value     set benchmark variable (can be repeated)
   --no-progress                 don't show benchmark progress indicator
+
+  Examples:
+    --set CPUSET=0            Runs benchmarks on CPU core 0.
+    --set CPUSET=0-2          Specifies that benchmarks should run on CPU cores 0 to 2.
+
+  Note: The CPUSET format should match the specifications of the 'taskset' command
 `, { arrayArgs: ['set', 'filter', 'exclude'], boolArgs: ['no-progress'] });
 
 if (!cli.optional.new || !cli.optional.old) {
@@ -69,10 +75,24 @@ if (showProgress) {
 
 (function recursive(i) {
   const job = queue[i];
-
-  const child = fork(path.resolve(__dirname, job.filename), cli.optional.set, {
-    execPath: cli.optional[job.binary],
-  });
+  const resolvedPath = path.resolve(__dirname, job.filename);
+
+  const cpuCore = cli.getCpuCoreSetting();
+  let child;
+  if (cpuCore !== null) {
+    const spawnArgs = ['-c', cpuCore, cli.optional[job.binary], resolvedPath, ...cli.optional.set];
+    child = spawn('taskset', spawnArgs, {
+      env: process.env,
+      stdio: ['inherit', 'pipe', 'pipe'],
+    });
+
+    child.stdout.pipe(process.stdout);
+    child.stderr.pipe(process.stderr);
+  } else {
+    child = fork(resolvedPath, cli.optional.set, {
+      execPath: cli.optional[job.binary],
+    });
+  }
 
   child.on('message', (data) => {
     if (data.type === 'report') {
diff --git a/benchmark/run.js b/benchmark/run.js
@@ -1,7 +1,7 @@
 'use strict';
 
 const path = require('path');
-const fork = require('child_process').fork;
+const { spawn, fork } = require('node:child_process');
 const CLI = require('./_cli.js');
 
 const cli = new CLI(`usage: ./node run.js [options] [--] <category> ...
@@ -17,7 +17,14 @@ const cli = new CLI(`usage: ./node run.js [options] [--] <category> ...
   test                      only run a single configuration from the options
                             matrix
   all                       each benchmark category is run one after the other
+
+  Examples:
+    --set CPUSET=0            Runs benchmarks on CPU core 0.
+    --set CPUSET=0-2          Specifies that benchmarks should run on CPU cores 0 to 2.
+
+  Note: The CPUSET format should match the specifications of the 'taskset' command on your system.
 `, { arrayArgs: ['set', 'filter', 'exclude'] });
+
 const benchmarks = cli.benchmarks();
 
 if (benchmarks.length === 0) {
@@ -40,10 +47,24 @@ if (format === 'csv') {
 
 (function recursive(i) {
   const filename = benchmarks[i];
-  const child = fork(
-    path.resolve(__dirname, filename),
-    cli.test ? ['--test'] : cli.optional.set,
-  );
+  const scriptPath = path.resolve(__dirname, filename);
+
+  const args = cli.test ? ['--test'] : cli.optional.set;
+  const cpuCore = cli.getCpuCoreSetting();
+  let child;
+  if (cpuCore !== null) {
+    child = spawn('taskset', ['-c', cpuCore, 'node', scriptPath, ...args], {
+      stdio: ['inherit', 'pipe', 'pipe'],
+    });
+
+    child.stdout.pipe(process.stdout);
+    child.stderr.pipe(process.stderr);
+  } else {
+    child = fork(
+      scriptPath,
+      args,
+    );
+  }
 
   if (format !== 'csv') {
     console.log();
diff --git a/doc/contributing/writing-and-running-benchmarks.md b/doc/contributing/writing-and-running-benchmarks.md
@@ -10,6 +10,7 @@
 * [Running benchmarks](#running-benchmarks)
   * [Running individual benchmarks](#running-individual-benchmarks)
   * [Running all benchmarks](#running-all-benchmarks)
+  * [Specifying CPU Cores for Benchmarks with run.js](#specifying-cpu-cores-for-benchmarks-with-runjs)
   * [Filtering benchmarks](#filtering-benchmarks)
   * [Comparing Node.js versions](#comparing-nodejs-versions)
   * [Comparing parameters](#comparing-parameters)
@@ -163,6 +164,33 @@ It is possible to execute more groups by adding extra process arguments.
 node benchmark/run.js assert async_hooks
 ```
 
+#### Specifying CPU Cores for Benchmarks with run.js
+
+When using `run.js` to execute a group of benchmarks,
+you can specify on which CPU cores the
+benchmarks should execute
+by using the `--set CPUSET=value` option.
+This controls the CPU core
+affinity for the benchmark process,
+potentially reducing
+interference from other processes and allowing
+for performance
+testing under specific hardware configurations.
+
+The `CPUSET` option utilizes the `taskset` command's format
+for setting CPU affinity, where `value` can be a single core
+number or a range of cores.
+
+Examples:
+
+* `node benchmark/run.js --set CPUSET=0` ... runs benchmarks on CPU core 0.
+* `node benchmark/run.js --set CPUSET=0-2` ...
+  specifies that benchmarks should run on CPU cores 0 to 2.
+
+Note: This option is only applicable when using `run.js`.
+Ensure the `taskset` command is available on your system
+and the specified `CPUSET` format matches its requirements.
+
 #### Filtering benchmarks
 
 `benchmark/run.js` and `benchmark/compare.js` have `--filter pattern` and
@@ -288,8 +316,16 @@ module, you can use the `--filter` option:_
   --old      ./old-node-binary  old node binary (required)
   --runs     30                 number of samples
   --filter   pattern            string to filter benchmark scripts
+  --exclude  pattern            excludes scripts matching <pattern> (can be
+                                repeated)
   --set      variable=value     set benchmark variable (can be repeated)
   --no-progress                 don't show benchmark progress indicator
+
+    Examples:
+    --set CPUSET=0            Runs benchmarks on CPU core 0.
+    --set CPUSET=0-2          Specifies that benchmarks should run on CPU cores 0 to 2.
+
+  Note: The CPUSET format should match the specifications of the 'taskset' command
 ```
 
 For analyzing the benchmark results, use [node-benchmark-compare][] or the R
