benchmark: conditionally use spawn with taskset for cpu pinning

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: https://github.com/nodejs/node/issues/52233
PR-URL: https://github.com/nodejs/node/pull/52253
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Raz Luvaton <rluvaton@gmail.com>
Reviewed-By: Yagiz Nizipli <yagiz.nizipli@sentry.io>

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;
+};

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 resolvedPath = path.resolve(__dirname, job.filename);
 
-  const child = fork(path.resolve(__dirname, job.filename), cli.optional.set, {
-    execPath: cli.optional[job.binary],
-  });
+  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') {

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();

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