path: root/common/scripts/is-cpu-isolated.sh

#!/bin/bash
#
# Author: Viresh Kumar <viresh.kumar@linaro.org>
#
# This script is used for isolating $1 (comma separated list of CPUs) CPUs from
# other kernel background activities.
#
# This runs task on the isolated CPUs and Figures out if CPUs are
# isolated or not by reading 'cat /proc/interrupts' for all interrupts.

# SCRIPT ARGUMENTS
# $1: CPUs to isolate (default 1), pass comma separated list here
# $2: number of samples to take (default 1)
# $3: Min Isolation Time Expected in seconds (default 10)

# Script arguments
ISOL_CPUS=1		# CPU to isolate, default 1. Comma-separated list of CPUs.
SAMPLE_COUNT=1		# How many samples to be taken
MIN_ISOLATION=10	# Minimum isolation expected

# Global variables
STRESS_DURATION=5000	# Run task for this duration
NON_ISOL_CPUS="0"	# CPU not to isolate, zero will always be there as we can't stop ticks on boot CPU.
DEBUG_SCRIPT=1		# Print debug messages, set 0 if not required
TASK="stress"		# Single threaded task to Run on Isolated CPUs
FUNC="all"		# Perform complete isolation test by default
SCRIPT_VERSION=1.0	# To track release version
RESULT="PASS"

# Variables to keep an eye on total interrupt counts
old_count=0
new_count=0


# 		ROUTINES
# ------------------------------------

# Print debug messages, set DEBUG_SCRIPT to 0 if not required
isdebug() {
	if [ $DEBUG_SCRIPT -eq 1 ]; then
		$*
	fi
}

# Calls routine $1 for each Isolated CPU with parameter CPU-number
for_each_isol_cpu() {
	for i in `echo $ISOL_CPUS | sed 's/,/ /g'`; do
		$1 $i
	done
}

# Get rid of cpufreq-timer activities, pass CPU number in $1
cpufreq_fix_governor() {
	# Remove governor's background timers, i.e. use performance governor
	if [ -d /sys/devices/system/cpu/cpu$1/cpufreq ]; then
		echo performance > /sys/devices/system/cpu/cpu$1/cpufreq/scaling_governor
	fi
}

# dump all interrupts on standard output
dump_interrupts() {
	[ ! $1 ] && printf "\nInitial dump of /proc/interrupts\n"
	[ $1 ] && printf "\n\nInterrupted: new dump of /proc/interrupts\n"
	echo "----------------------------------------------"

	cat /proc/interrupts
	printf "\n\n"
}

# Check $1 is isol cpu or not
is_isol_cpu() {
	for i in `echo $ISOL_CPUS | sed 's/,/ /g'`; do
		if [ $i = $1 ]
		then
			echo 1 # isol cpu found
		fi
	done

	echo 0 # non-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 $total_cpus ]
	do
		[ "$(is_isol_cpu $cpu)" == 0 ] && NON_ISOL_CPUS="$NON_ISOL_CPUS,$cpu"
		let cpu=cpu+1
	done

	isdebug echo "Isolate: CPU "$ISOL_CPUS" and leave others: "$NON_ISOL_CPUS
	isdebug echo ""
}

# Find total number of interrupts for
# - one CPU, pass cpu number as parameter
# - all CPUs, pass "ALL" as parameter
total_interrupts() {
	awk -v isolate_cpu="$1" '
	BEGIN {
		line=0;
	}

	# Find total CPUs, do only on first row
	NR==1 {
		cpus = NF;
		next;
	}

	# Fill array with interrupt counts
	{
		for (cpu = 0; cpu < cpus; cpu++) {
			irqs[cpu, line] = $(cpu+2);
		}
		line++;
	}

	# Count total interrupts:
	END {
		for (cpu = 0; cpu < cpus; cpu++) {
			for (j = 0; j < line; j++) {
				count[cpu] += irqs[cpu,j];
				# for debugging
				# printf "%d: %d: %d\n",cpu, j,irqs[cpu,j];
			}

			if (isolate_cpu == "ALL")
				printf "%d ",count[cpu]
			else if (cpu == isolate_cpu)
				printf "%d ",count[cpu]

		}
		printf "\n"
	}

	# File to process
' /proc/interrupts
}

# Create per-cpu data plane cpuset
create_dplane_cpuset() {
	# Create per-cpu cpuset and set important fields
	[ -d /dev/cpuset/dplane/cpu$1 ] || mkdir /dev/cpuset/dplane/cpu$1

	echo 0 > /dev/cpuset/dplane/cpu$1/$CPUSET_PREFIX"mems"
	echo $1 > /dev/cpuset/dplane/cpu$1/$CPUSET_PREFIX"cpus"
	echo 0 > /dev/cpuset/dplane/cpu$1/$CPUSET_PREFIX"sched_load_balance"

	# Move shell to isolated CPU
	echo $$ > /dev/cpuset/dplane/cpu$1/tasks

	# Start single cpu bound task
	stress -q --cpu 1 --timeout $STRESS_DURATION &

	# Move shell back to control plane CPU
	echo $$ > /dev/cpuset/cplane/tasks
}

# Remove per-cpu cpusets
remove_dplane_cpuset() {
	rmdir /dev/cpuset/dplane/cpu$1
}

# Update sysfs tunables to isolate CPU
update_sysfs_tunables() {
	# Call cpufreq_fix_governor for each isolated CPU
	for_each_isol_cpu cpufreq_fix_governor

	# 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

}

# 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

	# Update sysfs tunables
	update_sysfs_tunables

	# 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

	# 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 $ISOL_CPUS > /dev/cpuset/dplane/$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/$CPUSET_PREFIX"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"

	# Restart $ISOL_CPUS to migrate all tasks to CPU0
	# Commented-out: as we should get good numbers without this HACK
	#echo 0 > /sys/devices/system/cpu/cpu$ISOL_CPUS/online
	#echo 1 > /sys/devices/system/cpu/cpu$ISOL_CPUS/online

	# Call create_dplane_cpuset for each isolated CPU
	for_each_isol_cpu create_dplane_cpuset
}

# Count total number of interrupts for all isolated CPUs
count_interrupts_on_isol_cpus() {
	temp=($*)
	count=0

	for i in `echo $ISOL_CPUS | sed 's/,/ /g'`; do
		count=$(( $count + ${temp[i]} ))
	done

	echo $count
}

# Scan all interrupts again and find total for isolated-cores
refresh_interrupts() {
	# Get interrupt count for all CPUs
	interrupts=($(total_interrupts "ALL"))

	# Find total count of all interrupts on isol CPUs
	new_count=$(count_interrupts_on_isol_cpus ${interrupts[@]})

	[ $1 ] && isdebug echo "Counts for all CPUs: ${interrupts[@]}, total isol-cpus interrupts: $new_count"
}

# Sense infinite isolation
sense_infinite_isolation() {
	# process interrupts
	refresh_interrupts "print"
	old_count=$new_count

	# Get time as a UNIX timestamp (seconds elapsed since Jan 1, 1970 0:00 UTC)
	T1="$(date +%s)"

	while [ $new_count -eq $old_count ]
	do
		# process interrupts
		refresh_interrupts

		ps h -C $TASK -o pid > /dev/null
		if [ $? != 0 ]; then
			T2="$(date +%s)"
			T=$(($T2-$T1))

			echo "Quitting. Infinite Isolation detected: No interrupts for last: $T seconds"
			echo "test_case_id:Min-isolation $MIN_ISOLATION secs result:$RESULT measurement:$T units:secs"
			exit
		fi
	done

	# Interrupted, dump interrupts
	isdebug dump_interrupts 1
}

# routine to report 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 ""

	isdebug dump_interrupts

	# 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 two or more continuous ticks, skip them by sleeping for 100 ms.
		sleep .1

		# Sense infinite isolation
		sense_infinite_isolation

		T2="$(date +%s)"
		T=$(($T2-$T1))

		isdebug echo "End Time in seconds: ${T2}, time diff: "
		echo "$T seconds"
		isdebug echo ""

		# Calculations to show results
		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/remove all CPUsets, kill all instances of 'stess'
clear_cpusets() {
	isdebug echo ""
	isdebug echo "Started cleaning CPUSETS"
	isdebug echo "------------------------"
	isdebug echo ""

	#
	# Cleanup
	#

	# kill all instances of task
	for i in `ps | grep $TASK | 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
	for_each_isol_cpu remove_dplane_cpuset

	# delay required b/w cpu* cpusets and dplane cpuset for some reason,
	# other wise we get this: Device or resource busy
	sleep .1

	rmdir /dev/cpuset/cplane
	rmdir /dev/cpuset/dplane
}


# Execution starts from HERE

USAGE="Usage: $0 [-hv] [-ctfsd args] [-c <Comma separated isol cpulist (default cpu1)>] [-t <Task name for isolation (default stress)>] [-f <Function type options - isolate, duration, clear, nonisol_list, all (default all)>] [-s <Number of samples to take (default 1)>] [-d <Min Isolation duration expected in seconds (default 10)>]"

# Run isolation test for $FUNC
run_func()
{
	isdebug echo ""
	isdebug echo "Function type: $FUNC"

	case "$FUNC" in
		"isolate") 
		isolate_cpu
		;;

		"duration")
		get_isolation_duration
		;;

		"clear")
		clear_cpusets
		;;

		"nonisol_list")
		update_non_isol_cpus
		;;

		"all")
		isolate_cpu
		get_isolation_duration
		clear_cpusets
		;;

		*)
		echo "Invalid [-f] function type"
		;;
	esac
}

# Parse isol arguments
parse_arguments()
{
	while getopts hvc:t:f:s:d: arguments 2>/dev/null
	do
		case $arguments in
			h) # --help
				echo "$USAGE"
				exit 0
				;;

			v) # --script version
			       isdebug echo "$0 Version $SCRIPT_VERSION"
			       exit 0
			       ;;

			c) # --cpu (comma separated isol cpulist, default cpu1)
				ISOL_CPUS=$OPTARG
				;;

			t) # --task (task to run, default stress)
				TASK=$OPTARG
				;;

			f) # --func_type (Function to perform: Isolate, Duration,
			   #	Clear, Nonisol_list, all.  default all)
				FUNC=$OPTARG
				;;

			s) # --sample_count (no of samples to take, default 1)
				SAMPLE_COUNT=$OPTARG
				;;

			d) # --duration (min isolation time duration, default 10)
				MIN_ISOLATION=$OPTARG
				;;

			\?) # getopts issues an error message
				echo "$USAGE "
				exit 1
				;;
		esac
	done
}

# Parse isol arguments
parse_arguments $@

# Run isolation test for requested functionality
run_func