[tools][profiling] Add linux-perf profiling helper script

Change-Id: I8b84884257f20b1728e627f9c2e3643972f93514
Bug: 1299802
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3757345
Reviewed-by: Benoit Lize <lizeb@chromium.org>
Reviewed-by: Bruce Dawson <brucedawson@chromium.org>
Commit-Queue: Bruce Dawson <brucedawson@chromium.org>
Auto-Submit: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1029356}

docs/profiling.md

@@ -61,6 +61,10 @@ To stop profiling, press `Control-c` in the terminal window where `perf` is runn
 Tip for Googlers: running `gcert` first will make `pprof` run faster, and eliminate some useless spew to the terminal.
 ***
 
+If you want to profile all renderer processes use the custom `--renderer-cmd-prefix` profiling script:
+
+  $ src/out/Release/chrome --renderer-cmd-prefix="tools/profiling/linux-perf-renderer-cmd.sh"
+
 If you want to limit the profile to a single thread, run:
 
     $ ps -T -p <Process ID>

tools/profiling/linux-perf-renderer-cmd.sh

@@ -0,0 +1,60 @@
+#!/bin/bash
+# Copyright 2022 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+PERF_DATA_DIR="."
+PERF_DATA_PREFIX="chrome_renderer"
+RENDERER_ID="0"
+PERF_RECORD_FREQ="max"
+
+for i in "$@"; do
+  case $i in
+    --help)
+cat <<EOM
+Usage: path/to/chrome --renderer-cmd-prefix='${0} [OPTION]' [CHROME OPTIONS]
+
+This script is used  to run linux-perf for each renderer process.
+It generates perf.data files that can be read by pprof or linux-perf.
+
+Output: \$OUT_DIR/\$PREFIX_\$PPID_\$RENDERER_ID.perf.data
+
+Options:
+  --perf-data-dir=OUT_DIR    Change the location where perf.data is written.
+                             Default: '${PERF_DATA_DIR}'
+  --perf-data-prefix=PREFIX  Set a custom prefix for all generated perf.data
+                             files.
+                             Default: '${PERF_DATA_PREFIX}'
+  --perf-freq=FREQ           Sets the sampling frequency:
+                               'perf record --freq=FREQ'
+                             Default: '${PERF_RECORD_FREQ}'
+EOM
+      exit
+      ;;
+    --perf-data-dir=*)
+      PERF_DATA_DIR="${i#*=}"
+      shift
+    ;;
+    --perf-data-prefix=*)
+      PERF_DATA_PREFIX="${i#*=}"
+      shift
+    ;;
+    --perf-freq=*)
+      PERF_RECORD_FREQ="${i#*=}"
+      shift
+    ;;
+    --renderer-client-id=*)
+      # Don't shift this option since it is passed in (and used by) chrome.
+      RENDERER_ID="${i#*=}"
+    ;;
+    *)
+      ;;
+  esac
+done
+
+PERF_OUTPUT="$PERF_DATA_DIR/${PERF_DATA_PREFIX}_${PPID}_${RENDERER_ID}.perf.data"
+
+perf record \
+  --call-graph=fp --clockid=mono --freq="${PERF_RECORD_FREQ}" \
+  --output="${PERF_OUTPUT}" \
+  -- $@