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Sampat" To: mpe@ellerman.id.au, shuah@kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-kselftest@vger.kernel.org, psampat@linux.ibm.com, pratik.r.sampat@gmail.com Subject: [RFC 2/2] powerpc/selftest: Add support for cpuidle latency measurement Date: Fri, 11 Jun 2021 18:11:54 +0530 Message-Id: <20210611124154.56427-3-psampat@linux.ibm.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210611124154.56427-1-psampat@linux.ibm.com> References: <20210611124154.56427-1-psampat@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: wY7oG4CVDe1zknoZWTl8xzJAoQqqpae2 X-Proofpoint-ORIG-GUID: fZJEnuJb8bInLdbCaUJSfxOJN58NchOR X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391, 18.0.761 definitions=2021-06-11_05:2021-06-11,2021-06-11 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 malwarescore=0 bulkscore=0 phishscore=0 spamscore=0 lowpriorityscore=0 mlxlogscore=999 priorityscore=1501 clxscore=1015 suspectscore=0 mlxscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104190000 definitions=main-2106110080 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org The cpuidle latency selftest provides support to systematically extract, analyse and present IPI and timer based wakeup latencies for each CPU and each idle state available on the system. The selftest leverages test-cpuidle_latency module's debugfs interface to interact and extract latency information from the kernel. The selftest inserts the module if already not inserted, disables all the idle states and enables them one by one testing the following: 1. Keeping source CPU constant, iterate through all the CPUS measuring IPI latency for baseline (CPU is busy with cat /dev/random > /dev/null workload) and then when the CPU is allowed to be at rest 2. Iterating through all the CPUs, sending expected timer durations to be equivalent to the residency of the deepest idle state enabled and extracting the difference in time between the time of wakeup and the expected timer duration To run this test specifically: $ sudo make -C tools/testing/selftests \ TARGETS="powerpc/cpuidle_latency" run_tests There are a few optional arguments too that the script can take [-h ] [-m ] [-o ] [-v (run on all cpus)] Default Output location in: tools/testing/selftests/powerpc/cpuidle_latency/cpuidle_latency.log To run the test without re-compiling: $ cd tools/testing/selftest/powerpc/cpuidle_latency/ $ sudo ./cpuidle_latency.sh Signed-off-by: Pratik R. Sampat --- tools/testing/selftests/powerpc/Makefile | 1 + .../powerpc/cpuidle_latency/.gitignore | 2 + .../powerpc/cpuidle_latency/Makefile | 6 + .../cpuidle_latency/cpuidle_latency.sh | 419 ++++++++++++++++++ .../powerpc/cpuidle_latency/settings | 1 + 5 files changed, 429 insertions(+) create mode 100644 tools/testing/selftests/powerpc/cpuidle_latency/.gitignore create mode 100644 tools/testing/selftests/powerpc/cpuidle_latency/Makefile create mode 100755 tools/testing/selftests/powerpc/cpuidle_latency/cpuidle_latency.sh create mode 100644 tools/testing/selftests/powerpc/cpuidle_latency/settings diff --git a/tools/testing/selftests/powerpc/Makefile b/tools/testing/selftests/powerpc/Makefile index 0830e63818c1..71ce6fff867d 100644 --- a/tools/testing/selftests/powerpc/Makefile +++ b/tools/testing/selftests/powerpc/Makefile @@ -17,6 +17,7 @@ SUB_DIRS = alignment \ benchmarks \ cache_shape \ copyloops \ + cpuidle_latency \ dscr \ mm \ nx-gzip \ diff --git a/tools/testing/selftests/powerpc/cpuidle_latency/.gitignore b/tools/testing/selftests/powerpc/cpuidle_latency/.gitignore new file mode 100644 index 000000000000..987f8852dc59 --- /dev/null +++ b/tools/testing/selftests/powerpc/cpuidle_latency/.gitignore @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0-only +cpuidle_latency.log diff --git a/tools/testing/selftests/powerpc/cpuidle_latency/Makefile b/tools/testing/selftests/powerpc/cpuidle_latency/Makefile new file mode 100644 index 000000000000..04492b6d2582 --- /dev/null +++ b/tools/testing/selftests/powerpc/cpuidle_latency/Makefile @@ -0,0 +1,6 @@ +# SPDX-License-Identifier: GPL-2.0 +all: + +TEST_PROGS := cpuidle_latency.sh + +include ../../lib.mk diff --git a/tools/testing/selftests/powerpc/cpuidle_latency/cpuidle_latency.sh b/tools/testing/selftests/powerpc/cpuidle_latency/cpuidle_latency.sh new file mode 100755 index 000000000000..6b55167de488 --- /dev/null +++ b/tools/testing/selftests/powerpc/cpuidle_latency/cpuidle_latency.sh @@ -0,0 +1,419 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 +# +# CPU-Idle latency selftest provides support to systematically extract, +# analyse and present IPI and timer based wakeup latencies for each CPU +# and each idle state available on the system by leveraging the +# test-cpuidle_latency module +# +# Author: Pratik R. Sampat + +LOG=cpuidle_latency.log +MODULE=/lib/modules/$(uname -r)/kernel/arch/powerpc/kernel/test-cpuidle_latency.ko + +# Kselftest framework requirement - SKIP code is 4. +ksft_skip=4 + +VERBOSE=0 + +DISABLE=1 +ENABLE=0 + +helpme() +{ + printf "Usage: $0 [-h] [-todg args] + [-h ] + [-m ] + [-o ] + [-v ] + \n" + exit 2 +} + +parse_arguments() +{ + while getopts ht:m:o:vt:it: arg + do + case $arg in + h) # --help + helpme + ;; + m) # --mod-file + MODULE=$OPTARG + ;; + o) # output log files + LOG=$OPTARG + ;; + v) # Verbose mode - all threads of the CPU + VERBOSE=1 + ;; + \?) + helpme + ;; + esac + done +} + +ins_mod() +{ + debugfs_file=/sys/kernel/debug/latency_test/ipi_latency_ns + # Check if the module is already loaded + if [ -f "$debugfs_file" ]; then + printf "Module already loaded\n\n" + return 0 + fi + # Try to load the module + if [ ! -f "$MODULE" ]; then + printf "$MODULE module does not exist. Exitting\n" + exit $ksft_skip + fi + printf "Inserting $MODULE module\n\n" + insmod $MODULE + if [ $? != 0 ]; then + printf "Insmod $MODULE failed\n" + exit $ksft_skip + fi +} + +compute_average() +{ + arr=("$@") + sum=0 + size=${#arr[@]} + if [ $size == 0 ]; then + avg=0 + return 1 + fi + for i in "${arr[@]}" + do + sum=$((sum + i)) + done + avg=$((sum/size)) +} + +cpu_is_online() +{ + cpu=$1 + if [ ! -f "/sys/devices/system/cpu/cpu$cpu/online" ]; then + echo 1 + return + fi + status=$(cat /sys/devices/system/cpu/cpu$cpu/online) + echo $status +} + +# Perform operation on each CPU for the given state +# $1 - Operation: enable (0) / disable (1) +# $2 - State to enable +op_state() +{ + for ((cpu=0; cpu /sys/devices/system/cpu/cpu$cpu/cpuidle/state$2/disable + done +} + +cpuidle_enable_state() +{ + state=$1 + op_state $ENABLE $state +} + +cpuidle_disable_state() +{ + state=$1 + op_state $DISABLE $state +} + +# Enable/Disable all stop states for all CPUs +# $1 - Operation: enable (0) / disable (1) +op_cpuidle() +{ + for ((state=0; state /dev/null & + task_pid=$! + # Wait for the workload to achieve 100% CPU usage + sleep 1 + 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 $task_pid + wait $task_pid 2>/dev/null + fi +} + +# Incrementally Enable idle states one by one and compute the latency +run_ipi_tests() +{ + extract_latency + # Disable idle states for CPUs + op_cpuidle $DISABLE + + declare -a avg_arr + echo -e "--IPI Latency Test---" | tee -a $LOG + + echo -e "--Baseline IPI Latency measurement: CPU Busy--" >> $LOG + printf "%s %10s %12s\n" "SRC_CPU" "DEST_CPU" "IPI_Latency(ns)" >> $LOG + for cpu in "${core_arr[@]}" + do + local cpu_status=$(cpu_is_online $cpu) + if [ $cpu_status == 0 ]; then + continue + fi + ipi_test_once "baseline" $cpu + printf "%-3s %10s %12s\n" $src_cpu $cpu $ipi_latency >> $LOG + # Skip computing latency average from the source CPU to avoid bias + element_in "$cpu" "${first_core_arr[@]}" + if [ $? == 0 ]; then + continue + fi + avg_arr+=($ipi_latency) + done + compute_average "${avg_arr[@]}" + echo -e "Baseline Avg IPI latency(ns): $avg" | tee -a $LOG + + for ((state=0; state> $LOG + cpuidle_enable_state $state + printf "%s %10s %12s\n" "SRC_CPU" "DEST_CPU" "IPI_Latency(ns)" >> $LOG + for cpu in "${core_arr[@]}" + do + local cpu_status=$(cpu_is_online $cpu) + if [ $cpu_status == 0 ]; then + continue + fi + # Running IPI test and logging results + sleep 1 + ipi_test_once "test" $cpu + printf "%-3s %10s %12s\n" $src_cpu $cpu $ipi_latency >> $LOG + # Skip computing latency average from the source CPU to avoid bias + element_in "$cpu" "${first_core_arr[@]}" + if [ $? == 0 ]; then + continue + fi + avg_arr+=($ipi_latency) + done + compute_average "${avg_arr[@]}" + echo -e "Expected IPI latency(ns): ${latency_arr[$state]}" >> $LOG + echo -e "Observed Avg IPI latency(ns) - State ${state_name_arr[$state]}: $avg" | tee -a $LOG + cpuidle_disable_state $state + done +} + +# Extract the residency in microseconds and convert to nanoseconds. +# Add 200 ns so that the timer stays for a little longer than the residency +extract_residency() +{ + for ((state=0; state /dev/null & + task_pid=$! + # Wait for the workload to achieve 100% CPU usage + sleep 1 + fi + taskset -c $dest_cpu echo $3 > /sys/kernel/debug/latency_test/timeout_expected_ns + # Wait for the result to populate + sleep 0.1 + timeout_diff=$(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 $task_pid + wait $task_pid 2>/dev/null + fi +} + +run_timeout_tests() +{ + extract_residency + # Disable idle states for all CPUs + op_cpuidle $DISABLE + + declare -a avg_arr + echo -e "\n--Timeout Latency Test--" | tee -a $LOG + + echo -e "--Baseline Timeout Latency measurement: CPU Busy--" >> $LOG + printf "%s %10s %10s\n" "Wakeup_src" "Baseline_delay(ns)">> $LOG + for cpu in "${core_arr[@]}" + do + local cpu_status=$(cpu_is_online $cpu) + if [ $cpu_status == 0 ]; then + continue + fi + timeout_test_once "baseline" $cpu 1000000 + printf "%-3s %13s\n" $src_cpu $timeout_diff >> $LOG + avg_arr+=($timeout_diff) + done + compute_average "${avg_arr[@]}" + echo -e "Baseline Avg timeout diff(ns): $avg" | tee -a $LOG + + for ((state=0; state> $LOG + cpuidle_enable_state $state + printf "%s %10s %10s\n" "Wakeup_src" "Baseline_delay(ns)" "Delay(ns)" >> $LOG + for cpu in "${core_arr[@]}" + do + local cpu_status=$(cpu_is_online $cpu) + if [ $cpu_status == 0 ]; then + continue + fi + timeout_test_once "test" $cpu 1000000 + printf "%-3s %13s %18s\n" $src_cpu $baseline_timeout_diff $timeout_diff >> $LOG + avg_arr+=($timeout_diff) + done + compute_average "${avg_arr[@]}" + echo -e "Expected timeout(ns): ${residency_arr[$state]}" >> $LOG + echo -e "Observed Avg timeout diff(ns) - State ${state_name_arr[$state]}: $avg" | tee -a $LOG + cpuidle_disable_state $state + done +} + +declare -a residency_arr +declare -a latency_arr +declare -a core_arr +declare -a first_core_arr +declare -a state_name_arr + +parse_arguments $@ + +rm -f $LOG +touch $LOG +NUM_CPUS=$(nproc --all) +NUM_STATES=$(ls -1 /sys/devices/system/cpu/cpu0/cpuidle/ | wc -l) + +extract_core_information +extract_state_information + +ins_mod $MODULE + +run_ipi_tests +run_timeout_tests + +# Enable all idle states for all CPUs +op_cpuidle $ENABLE +printf "Removing $MODULE module\n" +printf "Full Output logged at: $LOG\n" +rmmod $MODULE + diff --git a/tools/testing/selftests/powerpc/cpuidle_latency/settings b/tools/testing/selftests/powerpc/cpuidle_latency/settings new file mode 100644 index 000000000000..e7b9417537fb --- /dev/null +++ b/tools/testing/selftests/powerpc/cpuidle_latency/settings @@ -0,0 +1 @@ +timeout=0