From nobody Mon Feb 9 03:11:15 2026 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 E62D012CD8B for ; Sun, 6 Apr 2025 02:40:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743907239; cv=none; b=X8U9YSGrIDCAAq867HIJS06XH9qb9c5WOlMFstqb4p0JBVX2EaJLHXIM+QMdhF4c488bgQAUie2Cs3XP2jxQRiS+k3Ixw3uhvEYMH9lyMJStfHH8QdxS54UULuXr4IReMevq2V0+D7a3xtMBcjr4WtalVEne4OJkHOgqxC5+kH4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743907239; c=relaxed/simple; bh=63QI201sgY1M7r1SkLAM/+CFB5wB+4V9arwwKPcMgHw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LQ8r2hm3x1Jvm1G+GhWZjcGRRGHau3jNr6TIzpw+qVqewm1LWAV8UVNr+v4pa+MJN7LSQlOGSexOBerSQqKf1c4tH44X+ma0H3WtMlyPvsVnrJk2AnbULYkJOYWKyRzw0LbFUiPlia8olWfjdlna9dzVr7Jy3g/MEbOopnncjGs= 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=d2+CoHiU; arc=none smtp.client-ip=170.10.129.124 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="d2+CoHiU" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1743907236; 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=0rjm7dsKH5H2OCApAESFBB2zqcpPfQudn9jh6O3bk7c=; b=d2+CoHiUJ47obuy9Nt+aVlAf5EjZgrhL2NPF7zq40eb/rfF4t/VdmlLNNmlD0j02H4t7Dp vh0VLs6CozOZBmn5g6k8KpR1wpkOhArajHlUd/WZ48hECNwB1y8lF1wFede08n1lWETRxm 9mKwtvbLZVHt6fdWsi7T4Sn2GZ8Q3TA= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-651-AheAZiZhN52DQAQGWW7H3Q-1; Sat, 05 Apr 2025 22:40:32 -0400 X-MC-Unique: AheAZiZhN52DQAQGWW7H3Q-1 X-Mimecast-MFC-AGG-ID: AheAZiZhN52DQAQGWW7H3Q_1743907230 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (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-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 5D9E41800EC5; Sun, 6 Apr 2025 02:40:30 +0000 (UTC) Received: from llong-thinkpadp16vgen1.westford.csb (unknown [10.22.64.19]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id DA38A1801A6D; Sun, 6 Apr 2025 02:40:27 +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 v3 2/2] selftests: memcg: Increase error tolerance of child memory.current check in test_memcg_protection() Date: Sat, 5 Apr 2025 22:40:10 -0400 Message-ID: <20250406024010.1177927-3-longman@redhat.com> In-Reply-To: <20250406024010.1177927-1-longman@redhat.com> References: <20250406024010.1177927-1-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 10.30.177.111 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. 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 bab826b6b7b0..8f4f2479650e 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