v8/tools/cpu.sh
jkummerow@chromium.org 45219bd84f Check in "cpu.sh" script to control CPU governor/cores on Linux
This can help with reproducing stability bugs or performance issues.

R=jarin@chromium.org

Review URL: https://codereview.chromium.org/485763003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23222 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-08-20 09:39:37 +00:00

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#!/bin/bash
# Copyright 2014 the V8 project authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
CPUPATH=/sys/devices/system/cpu
MAXID=$(cat $CPUPATH/present | awk -F- '{print $NF}')
set_governor() {
echo "Setting CPU frequency governor to \"$1\""
for (( i=0; i<=$MAXID; i++ )); do
echo "$1" > $CPUPATH/cpu$i/cpufreq/scaling_governor
done
}
dual_core() {
echo "Switching to dual-core mode"
for (( i=2; i<=$MAXID; i++ )); do
echo 0 > $CPUPATH/cpu$i/online
done
}
single_core() {
echo "Switching to single-core mode"
for (( i=1; i<=$MAXID; i++ )); do
echo 0 > $CPUPATH/cpu$i/online
done
}
all_cores() {
echo "Reactivating all CPU cores"
for (( i=2; i<=$MAXID; i++ )); do
echo 1 > $CPUPATH/cpu$i/online
done
}
case "$1" in
fast | performance)
set_governor "performance"
;;
slow | powersave)
set_governor "powersave"
;;
default | ondemand)
set_governor "ondemand"
;;
dualcore | dual)
dual_core
;;
singlecore | single)
single_core
;;
allcores | all)
all_cores
;;
*)
echo "Usage: $0 fast|slow|default|singlecore|dualcore|all"
exit 1
;;
esac