linux-kernel - [PATCH v3 2/2] perf test: Add test that command line period overrides sysfs/json values

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Message-ID: <20251109005959.2540616-2-irogers@google.com>
Date: Sat,  8 Nov 2025 16:59:59 -0800
From: Ian Rogers <irogers@...gle.com>
To: Namhyung Kim <namhyung@...nel.org>, Peter Zijlstra <peterz@...radead.org>, 
	Ingo Molnar <mingo@...hat.com>, Arnaldo Carvalho de Melo <acme@...nel.org>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Adrian Hunter <adrian.hunter@...el.com>, James Clark <james.clark@...aro.org>, 
	linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org
Cc: Ian Rogers <irogers@...gle.com>
Subject: [PATCH v3 2/2] perf test: Add test that command line period overrides
 sysfs/json values

The behavior of weak terms is subtle, add a test that they aren't
accidentally broken. The test finds an event with a weak 'period' and
then overrides it. In no such event is present then the test skips.

Signed-off-by: Ian Rogers <irogers@...gle.com>
---
v3: Add workaround in case the raw event is matched (Namhyung).
v2: Add more comments to the test code and reduce the line length (Namhyung).
---
 tools/perf/tests/shell/record_weak_term.sh | 37 ++++++++++++++++++++++
 1 file changed, 37 insertions(+)
 create mode 100755 tools/perf/tests/shell/record_weak_term.sh

diff --git a/tools/perf/tests/shell/record_weak_term.sh b/tools/perf/tests/shell/record_weak_term.sh
new file mode 100755
index 000000000000..811b00ffb47a
--- /dev/null
+++ b/tools/perf/tests/shell/record_weak_term.sh
@@ -0,0 +1,37 @@
+#!/bin/bash
+# record weak terms
+# SPDX-License-Identifier: GPL-2.0
+# Test that command line options override weak terms from sysfs or inbuilt json.
+set -e
+
+shelldir=$(dirname "$0")
+# shellcheck source=lib/setup_python.sh
+. "${shelldir}"/lib/setup_python.sh
+
+# Find the first event with a specified period, such as
+# "cpu_core/event=0x24,period=200003,umask=0xff/"
+event=$(perf list --json | $PYTHON -c '
+import json, sys
+for e in json.load(sys.stdin):
+    if "EventName" not in e or "/modifier" in e["EventName"]:
+        continue
+    if "Encoding" in e and "period=" in e["Encoding"]:
+        print(e["EventName"])
+        break
+')
+if [[ "$event" = "" ]]
+then
+  echo "Skip: No sysfs/json events with inbuilt period."
+  exit 2
+fi
+
+echo "Testing that for $event the period is overridden with 1000"
+perf list --detail "$event"
+if ! perf record -c 1000 -vv -e "$event" -o /dev/null true 2>&1 | \
+  grep -q -F '{ sample_period, sample_freq }   1000'
+then
+  echo "Fail: Unexpected verbose output and sample period"
+  exit 1
+fi
+echo "Success"
+exit 0
-- 
2.51.2.1041.gc1ab5b90ca-goog