Re: [PATCH 2/2] selftest/cpuidle: Add support for cpuidle latency measurement

On 7/7/20 9:29 AM, Pratik Rajesh Sampat wrote:

This patch adds support to trace IPI based and timer based wakeup latency from idle states

Latches onto the test-cpuidle_latency kernel module using the debugfs interface to send IPIs or schedule a timer based event, which in-turn populates the debugfs with the latency measurements.

Currently for the IPI and timer tests; first disable all idle states and then test for latency measurements incrementally enabling each state

Signed-off-by: Pratik Rajesh Sampat psampat@linux.ibm.com

tools/testing/selftests/Makefile | 1 + tools/testing/selftests/cpuidle/Makefile | 6 + tools/testing/selftests/cpuidle/cpuidle.sh | 240 +++++++++++++++++++++ tools/testing/selftests/cpuidle/settings | 1 + 4 files changed, 248 insertions(+) create mode 100644 tools/testing/selftests/cpuidle/Makefile create mode 100755 tools/testing/selftests/cpuidle/cpuidle.sh create mode 100644 tools/testing/selftests/cpuidle/settings

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile index 1195bd85af38..ab6cf51f3518 100644 --- a/tools/testing/selftests/Makefile +++ b/tools/testing/selftests/Makefile @@ -7,6 +7,7 @@ TARGETS += capabilities TARGETS += cgroup TARGETS += clone3 TARGETS += cpufreq +TARGETS += cpuidle TARGETS += cpu-hotplug TARGETS += drivers/dma-buf TARGETS += efivarfs diff --git a/tools/testing/selftests/cpuidle/Makefile b/tools/testing/selftests/cpuidle/Makefile new file mode 100644 index 000000000000..72fd5d2e974d --- /dev/null +++ b/tools/testing/selftests/cpuidle/Makefile @@ -0,0 +1,6 @@ +# SPDX-License-Identifier: GPL-2.0 +all:

+TEST_PROGS := cpuidle.sh

+include ../lib.mk diff --git a/tools/testing/selftests/cpuidle/cpuidle.sh b/tools/testing/selftests/cpuidle/cpuidle.sh new file mode 100755 index 000000000000..11666fe47c34 --- /dev/null +++ b/tools/testing/selftests/cpuidle/cpuidle.sh @@ -0,0 +1,240 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0

+LOG=cpuidle.log +MODULE=/lib/modules/$(uname -r)/kernel/drivers/cpuidle/test-cpuidle_latency.ko

+helpme() +{

• printf "Usage: $0 [-h] [-todg args]
• [-h <help>]
• [-m <location of the module>]
• [-o <location of the output>]
• \n"
• exit 2

+}

+parse_arguments() +{

• while getopts ht:m:o: arg
• do

• case $arg in
  

• 	h) # --help
  

• 		helpme
  

• 		;;
  

• 	m) # --mod-file
  

• 		MODULE=$OPTARG
  

• 		;;
  

• 	o) # output log files
  

• 		LOG=$OPTARG
  

• 		;;
  

• 	\?)
  

• 		helpme
  

• 		;;
  

• esac
  

• done

+}

+ins_mod() +{

• if [ ! -f "$MODULE" ]; then

• printf "$MODULE module does not exist. Exitting\n"
  

• exit 2
  

Please use ksft_skip code to indicate the test is being skipped.

• fi
• printf "Inserting $MODULE module\n\n"
• insmod $MODULE
• if [ $? != 0 ]; then

• printf "Insmod $MODULE failed\n"
  

• exit 2
  

This is fine since you expect to be able to load the module.

• fi

+}

+compute_average() +{

• arr=("$@")
• sum=0
• size=${#arr[@]}
• for i in "${arr[@]}"
• do

• sum=$((sum + i))
  

• done
• avg=$((sum/size))

+}

+# Disable all stop states +disable_idle() +{

• for ((cpu=0; cpu<NUM_CPUS; cpu++))
• do

• for ((state=0; state<NUM_STATES; state++))
  

• do
  

• 	echo 1 > /sys/devices/system/cpu/cpu$cpu/cpuidle/state$state/disable
  

• done
  

• done

+}

+# Enable the idle state supplied +# $1: State to enable +enable_state() +{

• for ((cpu=0; cpu<NUM_CPUS; cpu++))
• do

• echo 0 > /sys/devices/system/cpu/cpu$cpu/cpuidle/state$1/disable
  

• done

+}

+# Extract latency in microseconds and convert to nanoseconds +extract_latency() +{

• for ((state=0; state<NUM_STATES; state++))
• do

• latency=$(($(cat /sys/devices/system/cpu/cpu0/cpuidle/state$state/latency) * 1000))
  

• latency_arr+=($latency)
  

• done

+}

+# Run the IPI test +# $1 run for baseline - busy cpu or regular environment +# $2 destination cpu +ipi_test_once() +{

•    dest_cpu=$2
  

•    if [ "$1" = "baseline" ]; then
  

• 	# Keep the CPU busy
  

• 	taskset -c $dest_cpu yes "" > /dev/null &
  

• 	yes_pid=$!
  

•    fi
  

•    taskset 0x1 echo $dest_cpu > /sys/kernel/debug/latency_test/ipi_cpu_dest
  

•    ipi_latency=$(cat /sys/kernel/debug/latency_test/ipi_latency_ns)
  

•    src_cpu=$(cat /sys/kernel/debug/latency_test/ipi_cpu_src)
  

•    if [ "$1" = "baseline" ]; then
  

• 	kill $yes_pid
  

• 	wait $yes_pid 2>/dev/null
  

•    fi
  

+}

+# Incrementally Enable idle states one by one and compute the latency +run_ipi_tests() +{

•    extract_latency
  

•    disable_idle
  

•    declare -a avg_arr
  

•    declare -a baseline_avg_array
  

•    echo -e "--IPI Latency Test---" >> $LOG
  

•    for ((state=0; state<NUM_STATES; state++))
  

•    do
  

• 	echo -e "---Enabling state: $state---" >> $LOG
  

• 	enable_state $state
  

• 	printf "%s %10s %12s %12s\n" "SRC_CPU" "DEST_CPU" "Base_IPI_Latency(ns)" "IPI_Latency(ns)" >> $LOG
  

• 	unset avg_arr
  

• 	unset baseline_avg_arr
  

• 	for ((cpu=0; cpu<NUM_CPUS; cpu++))
  

• 	do
  

• 		# Running IPI test and logging results
  

• 		ipi_test_once "baseline" $cpu
  

• 		baseline_ipi_latency=$ipi_latency
  

• 		ipi_test_once "test" $cpu
  

• 		printf "%-3s %10s %12s %18s\n" $src_cpu $cpu $baseline_ipi_latency $ipi_latency >> $LOG
  

• 		avg_arr+=($ipi_latency)
  

• 		baseline_avg_arr+=($baseline_ipi_latency)
  

• 	done
  

• 	compute_average "${avg_arr[@]}"
  

• 	local avg_latency=$avg
  

• 	compute_average "${baseline_avg_arr[@]}"
  

• 	local baseline_avg_latency=$avg
  

• 	echo -e "Expected IPI latency(ns): ${latency_arr[$state]}" >> $LOG
  

• 	echo -e "Baseline Average IPI latency(ns): $baseline_avg_latency" >> $LOG
  

• 	echo -e "Observed Average IPI latency(ns): $avg_latency" >> $LOG
  

•    done
  

+}

+# Extract the residency in microseconds and convert to nanoseconds. +# Add 100 ns so that the timer stays for a little longer than the residency +extract_residency() +{

• for ((state=0; state<NUM_STATES; state++))
• do

• residency=$(($(cat /sys/devices/system/cpu/cpu0/cpuidle/state$state/residency) * 1000 + 200))
  

• residency_arr+=($residency)
  

• done

+}

+# Run the Timeout test +# $1 run for baseline - busy cpu or regular environment +# $2 destination cpu +# $3 timeout +timeout_test_once() +{

• dest_cpu=$2
• if [ "$1" = "baseline" ]; then

• # Keep the CPU busy
  

• taskset -c $dest_cpu yes "" > /dev/null &
  

• yes_pid=$!
  

• fi
• taskset -c $dest_cpu echo $3 > /sys/kernel/debug/latency_test/timeout_expected_ns
• sleep 0.1
• timeout_diff=$(cat /sys/kernel/debug/latency_test/timeout_diff_ns)
• src_cpu=$(cat /sys/kernel/debug/latency_test/timeout_cpu_src)
• if [ "$1" = "baseline" ]; then

• kill $yes_pid
  

• wait $yes_pid 2>/dev/null
  

• fi

+}

+run_timeout_tests() +{

• extract_residency
• disable_idle
• declare -a avg_arr
• declare -a baseline_avg_arr
• echo -e "\n--Timeout Latency Test--" >> $LOG
• for ((state=0; state<NUM_STATES; state++))
• do

• echo -e "---Enabling state: $state---" >> $LOG
  

• enable_state $state
  

• printf "%s %10s %10s\n" "Wakeup_src" "Baseline_delay(ns)" "Delay(ns)" >> $LOG
  

• unset avg_arr
  

• unset baseline_avg_arr
  

• for ((cpu=0; cpu<NUM_CPUS; cpu++))
  

• do
  

• 	timeout_test_once "baseline" $cpu ${residency_arr[$state]}
  

• 	local baseline_timeout_diff=$timeout_diff
  

• 	timeout_test_once "test" $cpu ${residency_arr[$state]}
  

• 	printf "%-3s %13s %18s\n" $src_cpu $baseline_timeout_diff $timeout_diff >> $LOG
  

• 	avg_arr+=($timeout_diff)
  

• 	baseline_avg_arr+=($baseline_timeout_diff)
  

• done
  

• compute_average "${baseline_avg_arr[@]}"
  

• local baseline_avg=$avg
  

• compute_average "${avg_arr[@]}"
  

• echo -e "Expected timeout(ns): ${residency_arr[$state]}" >> $LOG
  

• echo -e "Baseline Average timeout diff(ns): $baseline_avg" >> $LOG
  

• echo -e "Observed Average timeout diff(ns): $avg" >> $LOG
  

• done

+}

+declare -a residency_arr +declare -a latency_arr

+# Parse arguments +parse_arguments $@

+rm -f $LOG +touch $LOG +NUM_CPUS=$(nproc --all) +NUM_STATES=$(ls -1 /sys/devices/system/cpu/cpu0/cpuidle/ | wc -l)

+# Insert the module +ins_mod $MODULE

+printf "Started IPI latency tests\n" +run_ipi_tests

+printf "Started Timer latency tests\n" +run_timeout_tests

+printf "Removing $MODULE module\n" +printf "Output logged at: $LOG\n" +rmmod $MODULE diff --git a/tools/testing/selftests/cpuidle/settings b/tools/testing/selftests/cpuidle/settings new file mode 100644 index 000000000000..e7b9417537fb --- /dev/null +++ b/tools/testing/selftests/cpuidle/settings @@ -0,0 +1 @@ +timeout=0

thanks, -- Shuah