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

[Ian Rogers <irogers@google.com>]

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@google.com>
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}
-- 
2.55.0.795.g602f6c329a-goog