tools/testing/selftests/rcutorture/bin/jitter.sh

Source file repositories/reference/linux-study-clean/tools/testing/selftests/rcutorture/bin/jitter.sh

File Facts

System
Linux kernel
Corpus path
tools/testing/selftests/rcutorture/bin/jitter.sh
Extension
.sh
Size
2830 bytes
Lines
122
Domain
Support Tooling And Documentation
Bucket
tools
Inferred role
Support Tooling And Documentation: tools
Status
atlas-only

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

#!/bin/bash
# SPDX-License-Identifier: GPL-2.0+
#
# 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 jittering-path duration [ sleepmax [ spinmax ] ]
#
# me: Random-number-generator seed salt.
# duration: Time to run in seconds.
# jittering-path: Path to file whose removal will stop this script.
# sleepmax: Maximum microseconds to sleep, defaults to one second.
# spinmax: Maximum microseconds to spin, defaults to one millisecond.
#
# Copyright (C) IBM Corporation, 2016
#
# Authors: Paul E. McKenney <paulmck@linux.ibm.com>

me=$(($1 * 1000))
jittering=$2
duration=$3
sleepmax=${4-1000000}
spinmax=${5-1000}

n=1

starttime=`gawk 'BEGIN { print systime(); }' < /dev/null`

nohotplugcpus=
for i in /sys/devices/system/cpu/cpu[0-9]*
do
	if test -f $i/online
	then
		:
	else
		curcpu=`echo $i | sed -e 's/^[^0-9]*//'`
		nohotplugcpus="$nohotplugcpus $curcpu"
	fi
done

# Uses global variables startsecs, startns, endsecs, endns, and limit.
# Exit code is success for time not yet elapsed and failure otherwise.
function timecheck {
	local done=`awk -v limit=$limit \
			-v startsecs=$startsecs \
			-v startns=$startns \
			-v endsecs=$endsecs \
			-v endns=$endns < /dev/null '
		BEGIN {
			delta = (endsecs - startsecs) * 1000 * 1000;
			delta += int((endns - startns) / 1000);
			print delta >= limit;
		}'`
	return $done
}

while :
do
	# Check for done.
	t=`gawk -v s=$starttime 'BEGIN { print systime() - s; }' < /dev/null`
	if test "$t" -gt "$duration"
	then
		exit 0;
	fi

	# Check for stop request.
	if ! test -f "$jittering"
	then
		exit 1;

Annotation

Implementation Notes