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# This script is used for isolating $1 cpu from other kernel background
# activites. Currently this supports isolating a single core. This runs 'stress'
# test on the isolated CPU and Figures out if CPU is isolated or not by reading
# 'cat /proc/interrupts' for tick timers.
#
# Because it depends on the order of the columns in 'cat /proc/interrupts', it
# requires all CPUs to be online, otherwise things may go crazy.
#!/bin/bash
# Variable decided outcome of test, this is the minimum isolation we need.
ISOL_CPU=1 #CPU to isolate, default 1
SAMPLE_COUNT=1
MIN_ISOLATION=10
STRESS_DURATION=5000
NON_ISOL_CPUS="0" #CPU not to isolate, zero will always be there as we can't stop ticks on boot CPU.
RESULT="PASS"
if [ "$1" = "-h" -o "$1" = "--help" ]; then
echo "Usage: $0 <CPU to isolate (default 1)> <number of samples to take (default 1)> <Min Isolation Time Expected in seconds (default 10)>"
exit
fi
# Parse parameters
[ $1 ] && ISOL_CPU=$1
[ $2 ] && SAMPLE_COUNT=$2
[ $3 ] && MIN_ISOLATION=$3
# ROUTINES
debug_script=1
isdebug() {
if [ $debug_script -eq 1 ]; then
$*
fi
}
# routine to get tick count: Expects all CPUs to be online (otherwise column
# number may get wrong)
get_tick_count() { cat /proc/interrupts | grep arch_timer | grep 30 | sed 's/\s\+/ /g' | sed 's/^\s//g' | cut -d' ' -f$((2+$ISOL_CPU)) ; }
#For testing script on: x86
#get_tick_count() { cat /proc/interrupts | grep NMI | sed 's/\s\+/ /g' | sed 's/\s\+/ /g' | cut -d' ' -f$((2+$ISOL_CPU)) ; }
# update list of all non-ISOL CPUs
update_non_isol_cpus() {
total_cpus=`nproc --all --ignore=1` #ignore CPU 0 as we already have that
cpu=1
while [ $cpu -le $total_cpus ]
do
[ $cpu != $ISOL_CPU ] && NON_ISOL_CPUS="$NON_ISOL_CPUS,$cpu"
let cpu=cpu+1
done
isdebug echo "Isolate: CPU "$ISOL_CPU" and leave others: "$NON_ISOL_CPUS
isdebug echo ""
}
# routine to isolate a CPU
isolate_cpu() {
isdebug echo ""
isdebug echo "Started Isolating CPUs - via CPUSETS"
isdebug echo "------------------------------------"
isdebug echo ""
# Update list of non isol CPUs
update_non_isol_cpus
# Check that we have cpusets enabled in the kernel
if ! grep -q -s cpuset /proc/filesystems ; then
echo "Error: Kernel is lacking support for cpuset!"
exit 1
fi
# Remove governor's background timers, i.e. use performance governor
if [ -d /sys/devices/system/cpu/cpu$ISOL_CPU/cpufreq ]; then
echo performance > /sys/devices/system/cpu/cpu$ISOL_CPU/cpufreq/scaling_governor
fi
# Affine all irqs to CPU0
for i in `find /proc/irq/* -name smp_affinity`; do
echo 1 > $i > /dev/null;
done
# Try to disable sched_tick_max_deferment
if [ -d /sys/kernel/debug -a -f /sys/kernel/debug/sched_tick_max_deferment ]; then
echo -1 > /sys/kernel/debug/sched_tick_max_deferment
echo "sched_tick_max_deferment set to:" `cat /sys/kernel/debug/sched_tick_max_deferment`
else
sysctl -e kernel.sched_tick_max_deferment=-1
fi
# Move bdi writeback workqueues to CPU0
echo 1 > /sys/bus/workqueue/devices/writeback/cpumask
# Delay the annoying vmstat timer far away (in seconds)
sysctl vm.stat_interval=1000
# Delay the annoying vmstat timer far away (in centiseconds)
sysctl vm.dirty_writeback_centisecs=100000
# Delay the annoying vmstat timer far away (in centiseconds)
sysctl vm.dirty_expire_centisecs=100000
# Shutdown nmi watchdog as it uses perf events
sysctl -w kernel.watchdog=0
# make sure that the /dev/cpuset dir exits
# and mount the cpuset filesystem if needed
[ -d /dev/cpuset ] || mkdir /dev/cpuset
mount | grep /dev/cpuset > /dev/null || mount -t cpuset none /dev/cpuset
# Create 2 cpusets. One control plane and one data plane
[ -d /dev/cpuset/cplane ] || mkdir /dev/cpuset/cplane
[ -d /dev/cpuset/dplane ] || mkdir /dev/cpuset/dplane
# check if platform needs a prefix for cpuset
[ -f /dev/cpuset/cplane/cpus ] && CPUSET_PREFIX=""
[ -f /dev/cpuset/cplane/cpuset.cpus ] && CPUSET_PREFIX="cpuset."
# Give same mems to both
echo 0 > /dev/cpuset/cplane/$CPUSET_PREFIX"mems"
echo 0 > /dev/cpuset/dplane/$CPUSET_PREFIX"mems"
# Setup the cplane domain: CPU0
echo $NON_ISOL_CPUS > /dev/cpuset/cplane/$CPUSET_PREFIX"cpus"
# Setup the NOHZ domain: CPU1
echo $ISOL_CPU > /dev/cpuset/dplane/$CPUSET_PREFIX"cpus"
# Try to move all processes in top set to the cplane set.
for pid in `cat /dev/cpuset/tasks`; do
if [ -d /proc/$pid ]; then
echo $pid > /dev/cpuset/cplane/tasks 2>/dev/null
if [ $? != 0 ]; then
isdebug echo -n "Cannot move PID $pid: "
isdebug echo "$(cat /proc/$pid/status | grep ^Name | cut -f2)"
fi
fi
done
# Disable load balancing on top level (otherwise the child-sets' setting
# won't take effect.)
echo 0 > /dev/cpuset/sched_load_balance
# Enable load balancing withing the cplane domain
echo 1 > /dev/cpuset/cplane/$CPUSET_PREFIX"sched_load_balance"
# But disallow load balancing within the NOHZ domain
echo 0 > /dev/cpuset/dplane/$CPUSET_PREFIX"sched_load_balance"
# Quiesce CPU: i.e. migrate timers/hrtimers away
echo 1 > /dev/cpuset/dplane/$CPUSET_PREFIX"quiesce"
stress -q --cpu $ISOL_CPU --timeout $STRESS_DURATION &
# Restart $ISOL_CPU to migrate all tasks to CPU0
echo 0 > /sys/devices/system/cpu/cpu$ISOL_CPU/online
echo 1 > /sys/devices/system/cpu/cpu$ISOL_CPU/online
# Setup the NOHZ domain again: CPU1
echo $ISOL_CPU > /dev/cpuset/dplane/$CPUSET_PREFIX"cpus"
# Try to move all processes in top set to the cplane set.
for pid in `ps h -C stress -o pid`; do
echo $pid > /dev/cpuset/dplane/tasks 2>/dev/null
if [ $? != 0 ]; then
isdebug echo -n "dplane: Cannot move PID $pid: "
isdebug echo "$(cat /proc/$pid/status | grep ^Name | cut -f2)"
fi
done
}
# routine to get CPU isolation time
get_isolation_duration() {
isdebug echo ""
isdebug echo ""
isdebug echo "Capture Isolation time"
isdebug echo "----------------------"
isdebug echo "No. of samples requested:" $SAMPLE_COUNT", min isolation required:" $MIN_ISOLATION
isdebug echo ""
new_count=$(get_tick_count)
isdebug echo "initial count: " $new_count
old_count=$new_count
T2="$(date +%s)"
while [ $new_count -eq $old_count ]
do
new_count=$(get_tick_count)
ps h -C stress -o pid > /dev/null
if [ $? != 0 ]; then
T=$(($(date +%s)-$T2))
echo "Tick didn't got updated for stress duration:" $T
echo "Probably in infinite mode, quiting test"
echo "test_case_id:Min-isolation "$MIN_ISOLATION" secs result:"$RESULT" measurement:"$T" units:secs"
exit
fi
done
isdebug echo "count locked: " $new_count
# Get time as a UNIX timestamp (seconds elapsed since Jan 1, 1970 0:00 UTC)
T2="$(date +%s)"
x=0
AVG=0
MIN=99999999
MAX=0
while [ $x -lt $SAMPLE_COUNT ]
do
let x=x+1
T1=$T2
isdebug echo "Start Time in seconds: ${T1}"
# sometimes there are continuous ticks, skip them by sleeping for 100 ms.
sleep .1
# get count again after continuous ticks are skiped
old_count=$(get_tick_count)
new_count=$old_count
T2="$(date +%s)"
while [ $new_count -eq $old_count ]
do
new_count=$(get_tick_count)
ps h -C stress -o pid > /dev/null
if [ $? != 0 ]; then
T=$(($(date +%s)-$T2))
echo "Tick didn't got updated for stress duration:" $T
echo "Probably in infinite mode, quiting test"
echo "test_case_id:Min-isolation "$MIN_ISOLATION" secs result:PASS measurement:"$T" units:secs"
exit
fi
done
isdebug echo "sampling over: " $new_count
T2="$(date +%s)"
isdebug echo "End Time in seconds: ${T2}"
T=$(($T2-$T1))
isdebug echo "Time in seconds: "
echo $T
isdebug echo ""
let AVG=AVG+T
if [ $T -lt $MIN_ISOLATION -a $RESULT="PASS" ]; then
RESULT="FAIL"
fi
# Record minimum and maximum isolation
if [ $T -lt $MIN ]; then
MIN=$T
fi
if [ $T -gt $MAX ]; then
MAX=$T
fi
done
let AVG=AVG/$SAMPLE_COUNT
isdebug echo "Result:"
echo "test_case_id:Min-isolation "$MIN_ISOLATION" secs result:"$RESULT" measurement:"$AVG" units:secs"
echo "Min isolation is: "$MIN", Max isolation is: "$MAX" and Average isolation time is: "$AVG
isdebug echo ""
}
clear_cpusets() {
isdebug echo ""
isdebug echo "Started cleaning CPUSETS"
isdebug echo "------------------------"
isdebug echo ""
#
# Cleanup
#
# kill all instances of stress
for i in `ps | grep stress | sed 's/^\ *//g' | cut -d' ' -f1`;
do
kill -9 $i;
done
# Try to move all from cplane back to root
for pid in `cat /dev/cpuset/cplane/tasks`; do
if [ -d /proc/$pid ]; then
echo $pid > /dev/cpuset/tasks 2>/dev/null
if [ $? != 0 ]; then
isdebug echo -n "Cannot move PID $pid: "
isdebug echo "$(cat /proc/$pid/status | grep ^Name | cut -f2)"
fi
fi
done
# Remove the CPUsets
rmdir /dev/cpuset/cplane
rmdir /dev/cpuset/dplane
}
# tests to run
if [ $4 ]; then
if [ $4 -eq 1 ]; then
isolate_cpu
elif [ $4 -eq 2 ]; then
get_isolation_duration
elif [ $4 -eq 3 ]; then
clear_cpusets
else
update_non_isol_cpus
fi
else
isolate_cpu
get_isolation_duration
clear_cpusets
fi
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