doc: add benchmark/README.md and fix guide

* Write a new benchmark/README.md describing the benchmark
  directory layout and common API.
* Fix the moved benchmarking guide accordingly, add tips about how
  to get the help text from the benchmarking tools.

PR-URL: https://github.com/nodejs/node/pull/11237
Fixes: https://github.com/nodejs/node/issues/11190
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Andreas Madsen <amwebdk@gmail.com>

1 files changed, 246 insertions, 0 deletions

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+# Node.js Core Benchmarks
+
+This folder contains code and data used to measure performance
+of different Node.js implementations and different ways of
+writing JavaScript run by the built-in JavaScript engine.
+
+For a detailed guide on how to write and run benchmarks in this
+directory, see [the guide on benchmarks](../doc/guides/writing-and-running-benchmarks.md).
+
+## Table of Contents
+
+* [Benchmark directories](#benchmark-directories)
+* [Common API](#common-api)
+
+## Benchmark Directories
+
+<table>
+  <thead>
+    <tr>
+      <th>Directory</th>
+      <th>Purpose</th>
+    </tr>
+  </thead>
+  <tbody>
+    <tr>
+      <td>arrays</td>
+      <td>
+        Benchmarks for various operations on array-like objects,
+        including <code>Array</code>, <code>Buffer</code>, and typed arrays.
+      </td>
+    </tr>
+    <tr>
+      <td>assert</td>
+      <td>
+        Benchmarks for the <code>assert</code> subsystem.
+      </td>
+    </tr>
+    <tr>
+      <td>buffers</td>
+      <td>
+        Benchmarks for the <code>buffer</code> subsystem.
+      </td>
+    </tr>
+    <tr>
+      <td>child_process</td>
+      <td>
+        Benchmarks for the <code>child_process</code> subsystem.
+      </td>
+    </tr>
+    <tr>
+      <td>crypto</td>
+      <td>
+        Benchmarks for the <code>crypto</code> subsystem.
+      </td>
+    </tr>
+    <tr>
+      <td>dgram</td>
+      <td>
+        Benchmarks for the <code>dgram</code> subsystem.
+      </td>
+    </tr>
+    <tr>
+      <td>domain</td>
+      <td>
+        Benchmarks for the <code>domain</code> subsystem.
+      </td>
+    </tr>
+    <tr>
+      <td>es</td>
+      <td>
+        Benchmarks for various new ECMAScript features and their
+        pre-ES2015 counterparts.
+      </td>
+    </tr>
+    <tr>
+      <td>events</td>
+      <td>
+        Benchmarks for the <code>events</code> subsystem.
+      </td>
+    </tr>
+    <tr>
+      <td>fixtures</td>
+      <td>
+        Benchmarks fixtures used in various benchmarks throughout
+        the benchmark suite.
+      </td>
+    </tr>
+    <tr>
+      <td>fs</td>
+      <td>
+        Benchmarks for the <code>fs</code> subsystem.
+      </td>
+    </tr>
+    <tr>
+      <td>http</td>
+      <td>
+        Benchmarks for the <code>http</code> subsystem.
+      </td>
+    </tr>
+    <tr>
+      <td>misc</td>
+      <td>
+        Miscellaneous benchmarks and benchmarks for shared
+        internal modules.
+      </td>
+    </tr>
+    <tr>
+      <td>module</td>
+      <td>
+        Benchmarks for the <code>module</code> subsystem.
+      </td>
+    </tr>
+    <tr>
+      <td>net</td>
+      <td>
+        Benchmarks for the <code>net</code> subsystem.
+      </td>
+    </tr>
+    <tr>
+      <td>path</td>
+      <td>
+        Benchmarks for the <code>path</code> subsystem.
+      </td>
+    </tr>
+    <tr>
+      <td>process</td>
+      <td>
+        Benchmarks for the <code>process</code> subsystem.
+      </td>
+    </tr>
+    <tr>
+      <td>querystring</td>
+      <td>
+        Benchmarks for the <code>querystring</code> subsystem.
+      </td>
+    </tr>
+    <tr>
+      <td>streams</td>
+      <td>
+        Benchmarks for the <code>streams</code> subsystem.
+      </td>
+    </tr>
+    <tr>
+      <td>string_decoder</td>
+      <td>
+        Benchmarks for the <code>string_decoder</code> subsystem.
+      </td>
+    </tr>
+    <tr>
+      <td>timers</td>
+      <td>
+        Benchmarks for the <code>timers</code> subsystem, including
+        <code>setTimeout</code>, <code>setInterval</code>, .etc.
+      </td>
+    </tr>
+    <tr>
+      <td>tls</td>
+      <td>
+        Benchmarks for the <code>tls</code> subsystem.
+      </td>
+    </tr>
+    <tr>
+      <td>url</td>
+      <td>
+        Benchmarks for the <code>url</code> subsystem, including the legacy
+        <code>url</code> implementation and the WHATWG URL implementation.
+      </td>
+    </tr>
+    <tr>
+      <td>util</td>
+      <td>
+        Benchmarks for the <code>util</code> subsystem.
+      </td>
+    </tr>
+    <tr>
+      <td>vm</td>
+      <td>
+        Benchmarks for the <code>vm</code> subsystem.
+      </td>
+    </tr>
+  </tbody>
+</table>
+
+### Other Top-level files
+
+The top-level files include common dependencies of the benchmarks
+and the tools for launching benchmarks and visualizing their output.
+The actual benchmark scripts should be placed in their corresponding
+directories.
+
+* `_benchmark_progress.js`: implements the progress bar displayed
+  when running `compare.js`
+* `_cli.js`: parses the command line arguments passed to `compare.js`,
+  `run.js` and `scatter.js`
+* `_cli.R`: parses the command line arguments passed to `compare.R`
+* `_http-benchmarkers.js`: selects and runs external tools for benchmarking
+  the `http` subsystem.
+* `common.js`: see [Common API](#common-api).
+* `compare.js`: command line tool for comparing performance between different
+  Node.js binaries.
+* `compare.R`: R script for statistically analyzing the output of
+  `compare.js`
+* `run.js`: command line tool for running individual benchmark suite(s).
+* `scatter.js`: command line tool for comparing the performance
+  between different parameters in benchmark configurations,
+  for example to analyze the time complexity.
+* `scatter.R`: R script for visualizing the output of `scatter.js` with
+  scatter plots.
+
+## Common API
+
+The common.js module is used by benchmarks for consistency across repeated
+tasks. It has a number of helpful functions and properties to help with
+writing benchmarks.
+
+### createBenchmark(fn, configs[, options])
+
+See [the guide on writing benchmarks](../doc/guides/writing-and-running-benchmarks.md#basics-of-a-benchmark).
+
+### default\_http\_benchmarker
+
+The default benchmarker used to run HTTP benchmarks.
+See [the guide on writing HTTP benchmarks](../doc/guides/writing-and-running-benchmarks.md#creating-an-http-benchmark).
+
+
+### PORT
+
+The default port used to run HTTP benchmarks.
+See [the guide on writing HTTP benchmarks](../doc/guides/writing-and-running-benchmarks.md#creating-an-http-benchmark).
+
+### sendResult(data)
+
+Used in special benchmarks that can't use `createBenchmark` and the object
+it returns to accomplish what they need. This function reports timing
+data to the parent process (usually created by running `compare.js`, `run.js` or
+`scatter.js`).
+
+### v8ForceOptimization(method[, ...args])
+
+Force V8 to mark the `method` for optimization with the native function
+`%OptimizeFunctionOnNextCall()` and return the optimization status
+after that.
+
+It can be used to prevent the benchmark from getting disrupted by the optimizer
+kicking in halfway through. However, this could result in a less effective
+optimization. In general, only use it if you know what it actually does.