selftests/damon/damos_quota: make real expectation of quota exceeds

Patch series "selftests/damon: three fixes for false results".

Fix three DAMON selftest bugs that cause two and one false positive
failures and successes.

This patch (of 3):

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.

Link: https://lkml.kernel.org/r/20250225222333.505646-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20250225222333.505646-2-sj@kernel.org
Fixes: 51f58c9da14b ("selftests/damon: add a test for DAMOS quota")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/tools/testing/selftests/damon/damos_quota.py b/tools/testing/selftests/damon/damos_quota.py
index 7d4c6bb2e3cd27cf42d9d08439475cccf6ca3f08..57c4937aaed28552eb39f9511f2a8bd82a45f391 100755 (executable)
--- 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__':