is-cpu-isolated.sh: Enable tracking isolation for system with more than 2 CPUs

Till now this scripts was only useful for a system with two CPUs as there were
some assumptions. But there were requirements from multiple people about
supporting more platforms which might have more than two cores.

Hence this patch, it enables support for multiple cores and any core can be
isolated (leaving core 0, which can't be isolated in kernel as that's the boot
CPU).

Order of parameters is also changed based on what user may want. And so
nohz-isolation.yaml is updated in the same patch so that things don't break
inbetween.

Change-Id: I0656131a6a6d043e662d16f05dd08f172f2a3d9d
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

1 files changed, 53 insertions, 26 deletions

diff --git a/common/scripts/is-cpu-isolated.sh b/common/scripts/is-cpu-isolated.sh
index 3df4ec1..8caca66 100755
--- a/common/scripts/is-cpu-isolated.sh
+++ b/common/scripts/is-cpu-isolated.sh
@@ -1,24 +1,31 @@
+# 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
-RESULT="PASS"
 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 [ $2 ]; then
-	MIN_ISOLATION=$2
-fi
-
-# $1 is the number of samples required of isolation time, by default 1
 if [ "$1" = "-h" -o "$1" = "--help" ]; then
-	echo "Usage: $0 <number of samples to take> <Min Isolation Time Expected>"
+	echo "Usage: $0 <CPU to isolate (default 1)> <number of samples to take (default 1)> <Min Isolation Time Expected in seconds (default 10)>"
 	exit
-elif [ $1 ]; then
-	SAMPLE_COUNT=$1
-else
-	SAMPLE_COUNT=1
 fi
 
+# Parse parameters
+[ $1 ] && ISOL_CPU=$1
+[ $2 ] && SAMPLE_COUNT=$2
+[ $3 ] && MIN_ISOLATION=$3
+
 
 # ROUTINES
 debug_script=1
@@ -28,18 +35,37 @@ isdebug() {
 	fi
 }
 
-# routine to get tick count
-get_tick_count() { cat /proc/interrupts | grep arch_timer | grep 30 | sed 's/\s\+/ /g' | cut -d' ' -f4 ; }
+# 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' | cut -d' ' -f4 ; }
+#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_cpu1() {
+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!"
@@ -89,13 +115,15 @@ isolate_cpu1() {
 	[ -d /dev/cpuset/gp ] || mkdir /dev/cpuset/gp
 	[ -d /dev/cpuset/rt ] || mkdir /dev/cpuset/rt
 
-	# Setup the GP domain: CPU0
+	# Give same mems to both
 	echo 0 > /dev/cpuset/gp/mems
-	echo 0 > /dev/cpuset/gp/cpus
+	echo 0 > /dev/cpuset/rt/mems
+
+	# Setup the GP domain: CPU0
+	echo $NON_ISOL_CPUS > /dev/cpuset/gp/cpus
 
 	# Setup the NOHZ domain: CPU1
-	echo 0 > /dev/cpuset/rt/mems
-	echo 1 > /dev/cpuset/rt/cpus
+	echo $ISOL_CPU > /dev/cpuset/rt/cpus
 
 	# Try to move all processes in top set to the GP set.
 	for pid in `cat /dev/cpuset/tasks`; do
@@ -121,15 +149,14 @@ isolate_cpu1() {
 	# Quiesce CPU: i.e. migrate timers/hrtimers away
 	echo 1 > /dev/cpuset/rt/quiesce
 
-	stress -q --cpu 1 --timeout $STRESS_DURATION &
+	stress -q --cpu $ISOL_CPU --timeout $STRESS_DURATION &
 
-	# Restart CPU1 to migrate all tasks to CPU0
-	echo 0 > /sys/devices/system/cpu/cpu1/online
-	echo 1 > /sys/devices/system/cpu/cpu1/online
+	# 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 0 > /dev/cpuset/rt/mems
-	echo 1 > /dev/cpuset/rt/cpus
+	echo $ISOL_CPU > /dev/cpuset/rt/cpus
 
 	# Try to move all processes in top set to the GP set.
 	for pid in `ps h -C stress -o pid`; do
@@ -272,6 +299,6 @@ clear_cpusets() {
 }
 
 # tests to run
-isolate_cpu1
+isolate_cpu
 get_isolation_duration
 clear_cpusets