From nobody Fri Dec 19 14:06:25 2025 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 04B2318DF80 for ; Mon, 14 Apr 2025 02:13:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744596793; cv=none; b=ADpYbJAE05laSGg5tadUpaKWy7yTdYgamXsimZactjiMBhQEv6qMLTnJh1nAJLQP4s5XRSf0pepfda+m/oZRZCTVQTQW25icH/2e3pSYrF5lUQUGGdPw5bx2KYBf7z6Hdx/Cc9f9U0tyDP3VsgoBhGaPJR1fyAhJ84DPx0sS4QQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744596793; c=relaxed/simple; bh=M9u8GhzSuXNi2zRw5UTGbv3kuYBa26qTcGgdOIkDTc4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=qxL2eNpOsAH8kSL8BV2PkAStwtFZvpsZ6WO/W2cR0DX6WZ6SkR3iFIoIKnvOquf7c9OlCufKGEl39H85X2Boo2M/0mv/ZRAMi8Kh3gF+3bON5iE3s4F+jLSFI/DDbGDzOOyNUv/knJXuSAtdkJ6Y51LRY52MNK0J9afvolOoRJw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=hoxrYWzz; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="hoxrYWzz" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1744596790; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=cWd3wodO+vJYf6OkqNBmP1cg6W0V7cLt+fJ3yVah9lQ=; b=hoxrYWzzQBtDjqh8GvmMCewrbo+xpdoT/dbQ03tg61Yhq+JmeJyJPiQLExaFi4e/cKetyh kwgqOHgqFU0RPHGzFPaxzOJiu/W938KErzPGQvHvgRmXcrlvb7XvStHVMc8005bI5Xj+7X Wp//WBes4kTsTBcLKgbHqz6QaHXeGhI= Received: from mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-500-iG2B4VqjNJyB-FSbxmYGvw-1; Sun, 13 Apr 2025 22:13:09 -0400 X-MC-Unique: iG2B4VqjNJyB-FSbxmYGvw-1 X-Mimecast-MFC-AGG-ID: iG2B4VqjNJyB-FSbxmYGvw_1744596787 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id CCF5D1955DC5; Mon, 14 Apr 2025 02:13:06 +0000 (UTC) Received: from llong-thinkpadp16vgen1.westford.csb (unknown [10.22.88.48]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 11E63180B488; Mon, 14 Apr 2025 02:13:02 +0000 (UTC) From: Waiman Long To: Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton , Tejun Heo , =?UTF-8?q?Michal=20Koutn=C3=BD?= , Shuah Khan Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, Waiman Long Subject: [PATCH v6 2/2] selftests: memcg: Increase error tolerance of child memory.current check in test_memcg_protection() Date: Sun, 13 Apr 2025 22:12:49 -0400 Message-ID: <20250414021249.3232315-3-longman@redhat.com> In-Reply-To: <20250414021249.3232315-1-longman@redhat.com> References: <20250414021249.3232315-1-longman@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Content-Type: text/plain; charset="utf-8" The test_memcg_protection() function is used for the test_memcg_min and test_memcg_low sub-tests. This function generates a set of parent/child cgroups like: parent: memory.min/low =3D 50M child 0: memory.min/low =3D 75M, memory.current =3D 50M child 1: memory.min/low =3D 25M, memory.current =3D 50M child 2: memory.min/low =3D 0, memory.current =3D 50M After applying memory pressure, the function expects the following actual memory usages. parent: memory.current ~=3D 50M child 0: memory.current ~=3D 29M child 1: memory.current ~=3D 21M child 2: memory.current ~=3D 0 In reality, the actual memory usages can differ quite a bit from the expected values. It uses an error tolerance of 10% with the values_close() helper. Both the test_memcg_min and test_memcg_low sub-tests can fail sporadically because the actual memory usage exceeds the 10% error tolerance. Below are a sample of the usage data of the tests runs that fail. Child Actual usage Expected usage %err ----- ------------ -------------- ---- 1 16990208 22020096 -12.9% 1 17252352 22020096 -12.1% 0 37699584 30408704 +10.7% 1 14368768 22020096 -21.0% 1 16871424 22020096 -13.2% The current 10% error tolerenace might be right at the time test_memcontrol.c was first introduced in v4.18 kernel, but memory reclaim have certainly evolved quite a bit since then which may result in a bit more run-to-run variation than previously expected. Increase the error tolerance to 15% for child 0 and 20% for child 1 to minimize the chance of this type of failure. The tolerance is bigger for child 1 because an upswing in child 0 corresponds to a smaller %err than a similar downswing in child 1 due to the way %err is used in values_close(). Before this patch, a 100 test runs of test_memcontrol produced the following results: 17 not ok 1 test_memcg_min 22 not ok 2 test_memcg_low After applying this patch, there were no test failure for test_memcg_min and test_memcg_low in 100 test runs. However, these tests may still fail once in a while if the memory usage goes beyond the newly extended range. Signed-off-by: Waiman Long --- tools/testing/selftests/cgroup/test_memcontrol.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testi= ng/selftests/cgroup/test_memcontrol.c index 5a5dcbe57b56..2ef07b8fa718 100644 --- a/tools/testing/selftests/cgroup/test_memcontrol.c +++ b/tools/testing/selftests/cgroup/test_memcontrol.c @@ -495,10 +495,10 @@ static int test_memcg_protection(const char *root, bo= ol min) for (i =3D 0; i < ARRAY_SIZE(children); i++) c[i] =3D cg_read_long(children[i], "memory.current"); =20 - if (!values_close(c[0], MB(29), 10)) + if (!values_close(c[0], MB(29), 15)) goto cleanup; =20 - if (!values_close(c[1], MB(21), 10)) + if (!values_close(c[1], MB(21), 20)) goto cleanup; =20 if (c[3] !=3D 0) --=20 2.48.1