linux-kernel - [PATCH 1/3] selftests/damon/damos_quota: make real expectation of quota exceeds

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Message-Id: <20250225222333.505646-2-sj@kernel.org>
Date: Tue, 25 Feb 2025 14:23:31 -0800
From: SeongJae Park <sj@...nel.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: SeongJae Park <sj@...nel.org>,
	Shuah Khan <shuah@...nel.org>,
	damon@...ts.linux.dev,
	kernel-team@...a.com,
	linux-kernel@...r.kernel.org,
	linux-kselftest@...r.kernel.org,
	linux-mm@...ck.org,
	stable@...r.kernel.org
Subject: [PATCH 1/3] selftests/damon/damos_quota: make real expectation of quota exceeds

damos_quota.py assumes the quota will always exceeded.  But whether
quota will be exceeded or not depend on the monitoring results.
Actually the monitored workload has chaning access pattern and hence
sometimes the quota may not really be exceeded.  As a result, false
positive test failures happen.  Expect how much time the quota will be
exceeded by checking the monitoring results, and use it instead of the
naive assumption.

Fixes: 51f58c9da14b ("selftests/damon: add a test for DAMOS quota")
Cc: <stable@...r.kernel.org>
Signed-off-by: SeongJae Park <sj@...nel.org>
---
 tools/testing/selftests/damon/damos_quota.py | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/damon/damos_quota.py b/tools/testing/selftests/damon/damos_quota.py
index 7d4c6bb2e3cd..57c4937aaed2 100755
--- a/tools/testing/selftests/damon/damos_quota.py
+++ b/tools/testing/selftests/damon/damos_quota.py
@@ -51,16 +51,19 @@ def main():
         nr_quota_exceeds = scheme.stats.qt_exceeds
 
     wss_collected.sort()
+    nr_expected_quota_exceeds = 0
     for wss in wss_collected:
         if wss > sz_quota:
             print('quota is not kept: %s > %s' % (wss, sz_quota))
             print('collected samples are as below')
             print('\n'.join(['%d' % wss for wss in wss_collected]))
             exit(1)
+        if wss == sz_quota:
+            nr_expected_quota_exceeds += 1
 
-    if nr_quota_exceeds < len(wss_collected):
-        print('quota is not always exceeded: %d > %d' %
-              (len(wss_collected), nr_quota_exceeds))
+    if nr_quota_exceeds < nr_expected_quota_exceeds:
+        print('quota is exceeded less than expected: %d < %d' %
+              (nr_quota_exceeds, nr_expected_quota_exceeds))
         exit(1)
 
 if __name__ == '__main__':
-- 
2.39.5