91 lines
2.4 KiB
Bash
Executable file
91 lines
2.4 KiB
Bash
Executable file
#!/bin/bash
|
|
#
|
|
# Alternate sleeping and spinning on randomly selected CPUs. The purpose
|
|
# of this script is to inflict random OS jitter on a concurrently running
|
|
# test.
|
|
#
|
|
# Usage: jitter.sh me duration [ sleepmax [ spinmax ] ]
|
|
#
|
|
# me: Random-number-generator seed salt.
|
|
# duration: Time to run in seconds.
|
|
# sleepmax: Maximum microseconds to sleep, defaults to one second.
|
|
# spinmax: Maximum microseconds to spin, defaults to one millisecond.
|
|
#
|
|
# This program is free software; you can redistribute it and/or modify
|
|
# it under the terms of the GNU General Public License as published by
|
|
# the Free Software Foundation; either version 2 of the License, or
|
|
# (at your option) any later version.
|
|
#
|
|
# This program is distributed in the hope that it will be useful,
|
|
# but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
# GNU General Public License for more details.
|
|
#
|
|
# You should have received a copy of the GNU General Public License
|
|
# along with this program; if not, you can access it online at
|
|
# http://www.gnu.org/licenses/gpl-2.0.html.
|
|
#
|
|
# Copyright (C) IBM Corporation, 2016
|
|
#
|
|
# Authors: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
|
|
|
|
me=$(($1 * 1000))
|
|
duration=$2
|
|
sleepmax=${3-1000000}
|
|
spinmax=${4-1000}
|
|
|
|
n=1
|
|
|
|
starttime=`awk 'BEGIN { print systime(); }' < /dev/null`
|
|
|
|
while :
|
|
do
|
|
# Check for done.
|
|
t=`awk -v s=$starttime 'BEGIN { print systime() - s; }' < /dev/null`
|
|
if test "$t" -gt "$duration"
|
|
then
|
|
exit 0;
|
|
fi
|
|
|
|
# Set affinity to randomly selected CPU
|
|
cpus=`ls /sys/devices/system/cpu/*/online |
|
|
sed -e 's,/[^/]*$,,' -e 's/^[^0-9]*//' |
|
|
grep -v '^0*$'`
|
|
cpumask=`awk -v cpus="$cpus" -v me=$me -v n=$n 'BEGIN {
|
|
srand(n + me + systime());
|
|
ncpus = split(cpus, ca);
|
|
curcpu = ca[int(rand() * ncpus + 1)];
|
|
mask = lshift(1, curcpu);
|
|
if (mask + 0 <= 0)
|
|
mask = 1;
|
|
printf("%#x\n", mask);
|
|
}' < /dev/null`
|
|
n=$(($n+1))
|
|
if ! taskset -p $cpumask $$ > /dev/null 2>&1
|
|
then
|
|
echo taskset failure: '"taskset -p ' $cpumask $$ '"'
|
|
exit 1
|
|
fi
|
|
|
|
# Sleep a random duration
|
|
sleeptime=`awk -v me=$me -v n=$n -v sleepmax=$sleepmax 'BEGIN {
|
|
srand(n + me + systime());
|
|
printf("%06d", int(rand() * sleepmax));
|
|
}' < /dev/null`
|
|
n=$(($n+1))
|
|
sleep .$sleeptime
|
|
|
|
# Spin a random duration
|
|
limit=`awk -v me=$me -v n=$n -v spinmax=$spinmax 'BEGIN {
|
|
srand(n + me + systime());
|
|
printf("%06d", int(rand() * spinmax));
|
|
}' < /dev/null`
|
|
n=$(($n+1))
|
|
for i in {1..$limit}
|
|
do
|
|
echo > /dev/null
|
|
done
|
|
done
|
|
|
|
exit 1
|