----- On Oct 4, 2018, at 1:25 PM, Mathieu Desnoyers mathieu.desnoyers@efficios.com wrote:

Hi Naresh,

----- On Oct 4, 2018, at 5:34 AM, naresh kamboju naresh.kamboju@linaro.org wrote:

...

Restart able sequences test "run_param_test.sh" test case running long on target devices. I have listed test duration on x86_64, arm64 and arm32.

Considering that failures only happen randomly when the scheduler preempts threads running in a rseq critical section, we need to have some amount of repetition in there.

There are however other aspects that we might want to tweak based on the detected system configuration.

As a baseline, run_param_test.sh completes in 3m49s on my 16-core x86-64 (+hyperthreading).

I see that your x86-64 completes in 10m. We might want to tweak the number of threads used in each test (currently always at its default of 200) based on the number of detected cpus. The formula nr_cpus * 5 is an estimate that would be close to the 200 threads that are configured to run in about 4m on my main test system. It can be specified to param_test with the following option:

[-t N] Number of threads (default 200)

The goal behind having 5 threads per cpu is to ensure the scheduler will preempt the running threads frequently enough.

I am really tempted to adapt the number of threads based on the number of detected cpus rather than make the number of loops smaller, so we can keep the current amount of work per cpu (and therefore likelihood to trigger a rseq failure scenario).

Thoughts ?

Something like the following diff:

diff --git a/tools/testing/selftests/rseq/run_param_test.sh b/tools/testing/selftests/rseq/run_param_test.sh index 3acd6d75ff9f..e426304fd4a0 100755 --- a/tools/testing/selftests/rseq/run_param_test.sh +++ b/tools/testing/selftests/rseq/run_param_test.sh @@ -1,6 +1,8 @@ #!/bin/bash # SPDX-License-Identifier: GPL-2.0+ or MIT

+NR_CPUS=`grep '^processor' /proc/cpuinfo | wc -l` + EXTRA_ARGS=${@}

OLDIFS="$IFS" @@ -28,15 +30,16 @@ IFS="$OLDIFS"

REPS=1000 SLOW_REPS=100 +NR_THREADS=$((6*${NR_CPUS}))

function do_tests() { local i=0 while [ "$i" -lt "${#TEST_LIST[@]}" ]; do echo "Running test ${TEST_NAME[$i]}" - ./param_test ${TEST_LIST[$i]} -r ${REPS} ${@} ${EXTRA_ARGS} || exit 1 + ./param_test ${TEST_LIST[$i]} -r ${REPS} -t ${NR_THREADS} ${@} ${EXTRA_ARGS} || exit 1 echo "Running compare-twice test ${TEST_NAME[$i]}" - ./param_test_compare_twice ${TEST_LIST[$i]} -r ${REPS} ${@} ${EXTRA_ARGS} || exit 1 + ./param_test_compare_twice ${TEST_LIST[$i]} -r ${REPS} -t ${NR_THREADS} ${@} ${EXTRA_ARGS} || exit 1 let "i++" done }