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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Shakeel Butt , linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20260723134158.1473841-1-nirmoyd@nvidia.com> <20260723162133.877125-1-nirmoyd@nvidia.com> From: Mathieu Desnoyers Content-Language: en-US In-Reply-To: <20260723162133.877125-1-nirmoyd@nvidia.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: YQZPR01CA0049.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:c01:88::13) To YT2PR01MB9175.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:b01:be::5) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: YT2PR01MB9175:EE_|YT4PR01MB10692:EE_ X-MS-Office365-Filtering-Correlation-Id: d58e9a39-32ae-415d-b1b5-08dee8d7cab5 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|23010399003|366016|7416014|376014|1800799024|56012099006|10067099003|4143699003|18002099003|22082099003; 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My series attack the same issue you are trying to solve without >> increasing overhead when reading those counters. > > I tested the v20 series on a dual-socket system with 352 CPUs and > 64 KiB pages. > > On the v7.2-rc4 test kernel without the series, getrusage03 failed > 10/10: > > TFAIL: child.children = 270336, expected 307200 > > With v20, it also failed 10/10: > > TFAIL: initial.children = 0, expected 102400 > TFAIL: child.children = 262144, expected 307200 > > In v20, get_mm_hiwater_rss() still calls get_mm_rss(), which uses an > approximate counter read. The series did not help this test. Correct, my hierarchical counters keep a approximation there, but is improves the accuracy of the approximation (worse case inaccuracy limited by the topology). What is this test validating ? Does it actually matter for a real-life use-case, or is it just the test being too strict ? What is the overhead impact of your change from approximated counter read to a precise sum on this /proc ABI ? Thanks, Mathieu > > Let me know if you want to me to try out something else. > > Thanks, > Nirmoy -- Mathieu Desnoyers EfficiOS Inc. https://www.efficios.com