Hi Pratik,
On Fri, Jul 17, 2020 at 02:48:01PM +0530, 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
A few comments below.
tools/testing/selftests/Makefile | 1 + tools/testing/selftests/cpuidle/Makefile | 6 + tools/testing/selftests/cpuidle/cpuidle.sh | 257 +++++++++++++++++++++ tools/testing/selftests/cpuidle/settings | 1 + 4 files changed, 265 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
[..skip..]
+ins_mod() +{
- if [ ! -f "$MODULE" ]; then
printf "$MODULE module does not exist. Exitting\n"
If the module has been compiled into the kernel (due to a localyesconfig, for instance), then it is unlikely that we will find it in /lib/modules. Perhaps you want to check if the debugfs directories created by the module exist, and if so, print a message saying that the modules is already loaded or some such?
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=${#arr[@]}
- for i in "${arr[@]}"
- do
sum=$((sum + i))- done
- avg=$((sum/size))
It would be good to assert that "size" isn't 0 here.
+}
+# Disable all stop states +disable_idle() +{
- for ((cpu=0; cpu<NUM_CPUS; cpu++))
- do
for ((state=0; state<NUM_STATES; state++))doecho 1 > /sys/devices/system/cpu/cpu$cpu/cpuidle/state$state/disable
So, on offlined CPUs, we won't see /sys/devices/system/cpu/cpu$cpu/cpuidle/state$state directory. You should probably perform this operation only on online CPUs.
done- done
+}
+# 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<NUM_CPUS; cpu++))
- do
echo $1 > /sys/devices/system/cpu/cpu$cpu/cpuidle/state$2/disable
Ditto
- done
+}
This is a helper function. For better readability of the main code you can define the following wrappers and use them.
cpuidle_enable_state() { state=$1 op_state 1 $state }
cpuidle_disable_state() { state=$1 op_state 0 $state
}
[..snip..]
+run_ipi_tests() +{
extract_latencydisable_idledeclare -a avg_arrecho -e "--IPI Latency Test---" >> $LOGecho -e "--Baseline IPI Latency measurement: CPU Busy--" >> $LOGprintf "%s %10s %12s\n" "SRC_CPU" "DEST_CPU" "IPI_Latency(ns)" >> $LOGfor ((cpu=0; cpu<NUM_CPUS; cpu++))doipi_test_once "baseline" $cpuprintf "%-3s %10s %12s\n" $src_cpu $cpu $ipi_latency >> $LOGavg_arr+=($ipi_latency)donecompute_average "${avg_arr[@]}"echo -e "Baseline Average IPI latency(ns): $avg" >> $LOGfor ((state=0; state<NUM_STATES; state++))dounset avg_arrecho -e "---Enabling state: $state---" >> $LOGop_state 0 $stateprintf "%s %10s %12s\n" "SRC_CPU" "DEST_CPU" "IPI_Latency(ns)" >> $LOGfor ((cpu=0; cpu<NUM_CPUS; cpu++))do
If a CPU is offline, then we should skip it here.
# Running IPI test and logging resultssleep 1ipi_test_once "test" $cpuprintf "%-3s %10s %12s\n" $src_cpu $cpu $ipi_latency >> $LOGavg_arr+=($ipi_latency)donecompute_average "${avg_arr[@]}"echo -e "Expected IPI latency(ns): ${latency_arr[$state]}" >> $LOGecho -e "Observed Average IPI latency(ns): $avg" >> $LOGop_state 1 $statedone+}
+# Extract the residency in microseconds and convert to nanoseconds. +# Add 100 ns so that the timer stays for a little longer than the residency +extract_residency() +{
- for ((state=0; state<NUM_STATES; state++))
- do
residency=$(($(cat /sys/devices/system/cpu/cpu0/cpuidle/state$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 busytaskset -c $dest_cpu cat /dev/random > /dev/null &task_pid=$!# Wait for the workload to achieve 100% CPU usagesleep 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_pidwait $task_pid 2>/dev/null- fi
+}
+run_timeout_tests() +{
- extract_residency
- disable_idle
- declare -a avg_arr
- echo -e "\n--Timeout Latency Test--" >> $LOG
- echo -e "--Baseline Timeout Latency measurement: CPU Busy--" >> $LOG
- printf "%s %10s %10s\n" "Wakeup_src" "Baseline_delay(ns)">> $LOG
- for ((cpu=0; cpu<NUM_CPUS; cpu++))
- do
Again only perform this on online CPUs.
timeout_test_once "baseline" $cpu ${residency_arr[0]}printf "%-3s %13s\n" $src_cpu $timeout_diff >> $LOGavg_arr+=($timeout_diff)- done
- compute_average "${avg_arr[@]}"
- echo -e "Baseline Average timeout diff(ns): $avg" >> $LOG
- for ((state=0; state<NUM_STATES; state++))
- do
echo -e "---Enabling state: $state---" >> $LOGop_state 0 $stateprintf "%s %10s %10s\n" "Wakeup_src" "Baseline_delay(ns)" "Delay(ns)" >> $LOGunset avg_arrfor ((cpu=0; cpu<NUM_CPUS; cpu++))do
Ditto.
timeout_test_once "test" $cpu ${residency_arr[$state]}printf "%-3s %13s %18s\n" $src_cpu $baseline_timeout_diff $timeout_diff >> $LOGavg_arr+=($timeout_diff)donecompute_average "${avg_arr[@]}"echo -e "Expected timeout(ns): ${residency_arr[$state]}" >> $LOGecho -e "Observed Average timeout diff(ns): $avg" >> $LOGop_state 1 $state- done
+}
-- Thanks and Regards gautham.