Re: [PATCH v1] perf tests: Restore -p flag to lock contention test

[Thomas Richter]

On 7/8/26 19:53, Ian Rogers wrote:
> Commit ae42a2a2a3ae ("perf tests: Speed up lock contention analysis shell test")
> in linux-next heavily optimized the test runtimes by switching the workload from
> the default of 10 process groups down to 1 (`perf bench sched messaging -g 1`).
> 
> However, this change inadvertently dropped the original `-p` flag, causing the
> benchmark to default to `socketpair()` instead of `pipe()`. While `socketpair()`
> still generates some lock events on x86, it fails to trigger enough samples on
> architectures like s390, causing the test suite to fail due to lack of captured
> data.
> 
> Restore the omitted `-p` pipe flag. The test retains the massive speedups
> achieved through the `-g 1` scaling, while producing a massive density of lock
> events across all architectures to fully satisfy the BPF trace filtering logic.
> 
> Fixes: ae42a2a2a3ae ("perf tests: Speed up lock contention analysis shell test")
> Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
> Assisted-by: Antigravity:gemini-3.1-pro
> ---
>  tools/perf/tests/shell/lock_contention.sh | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/tests/shell/lock_contention.sh b/tools/perf/tests/shell/lock_contention.sh
> index ba598370be73..5df9a0cd48a3 100755
> --- a/tools/perf/tests/shell/lock_contention.sh
> +++ b/tools/perf/tests/shell/lock_contention.sh
> @@ -11,7 +11,8 @@ errout=$(mktemp /tmp/__perf_test.errout.XXXXX)
>  
>  # Workload to generate lock contention.
>  # Using 1 group (-g 1) keeps runtime low while generating sufficient lock events.
> -msg_workload="perf bench sched messaging -g 1"
> +# We include -p (pipes) because socketpairs don't generate enough lock events on s390.
> +msg_workload="perf bench sched messaging -g 1 -p"
>  
>  cleanup() {
>  	rm -f ${perfdata}

Tested-by: Thomas Richter <tmricht@xxxxxxxxxxxxx>

Thanks a lot

-- 
Thomas Richter, Dept 3303, IBM s390 Linux Development, Boeblingen, Germany
--
IBM Deutschland Research & Development GmbH

Vorsitzender des Aufsichtsrats: Wolfgang Wendt

Geschäftsführung: David Faller

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