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

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Adding the `-p` (pipe) flag to the global workload unconditionally disables the stack filter tests.
--

--- Patch [1]: [PATCH v1] perf tests: Restore -p flag to lock contention test ---
commit b4bb7054950dea7123c601308622ddcd596c94cf
Author: Ian Rogers <irogers@google.com>

perf tests: Restore -p flag to lock contention test

This commit restores the -p flag to the perf bench sched messaging workload
used by the lock contention test. By defaulting to pipes instead of
socketpairs, it ensures architectures like s390 generate sufficient lock
events for the BPF trace filtering logic to pass.

> diff --git a/tools/perf/tests/shell/lock_contention.sh b/tools/perf/tests/shell/lock_contention.sh
> index ba598370be738..5df9a0cd48a34 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"

[Severity: Medium]
Will adding the -p flag cause test_stack_filter() and 
test_aggr_task_stack_filter() to unconditionally skip?

These tests explicitly verify filtering behavior by searching for unix_stream 
locks in tools/perf/tests/shell/lock_contention.sh:

test_stack_filter()
{
	echo "Testing perf lock contention --callstack-filter (w/ unix_stream)"
	perf lock contention -i ${perfdata} -v -q 2> ${result}
	if [ "$(grep -c unix_stream "${result}")" = "0" ]; then
		echo "[Skip] Could not find 'unix_stream'"
		return
	fi

Since pipes use pipe locks instead of AF_UNIX stream socket locks 
(unix_stream), the shared perfdata profile will no longer contain these locks. 

Does this mean we lose test suite coverage for the --callstack-filter option 
across all architectures because the grep will always return 0?

>  
>  cleanup() {
>  	rm -f ${perfdata}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260708175311.858850-1-irogers@google.com?part=1