From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7FCC2D2D105 for ; Tue, 13 Jan 2026 13:51:56 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E277F6B0005; Tue, 13 Jan 2026 08:51:55 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id DD50A6B0089; Tue, 13 Jan 2026 08:51:55 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C61FF6B008A; Tue, 13 Jan 2026 08:51:55 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id B61686B0005 for ; Tue, 13 Jan 2026 08:51:55 -0500 (EST) Received: from smtpin07.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 6561F160157 for ; Tue, 13 Jan 2026 13:51:55 +0000 (UTC) X-FDA: 84327078990.07.FDDBF45 Received: from YQZPR01CU011.outbound.protection.outlook.com (mail-canadaeastazon11020122.outbound.protection.outlook.com [52.101.191.122]) by imf23.hostedemail.com (Postfix) with ESMTP id 6D16414000F for ; Tue, 13 Jan 2026 13:51:52 +0000 (UTC) Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=efficios.com header.s=selector1 header.b=CiSbhKYJ; spf=pass (imf23.hostedemail.com: domain of mathieu.desnoyers@efficios.com designates 52.101.191.122 as permitted sender) smtp.mailfrom=mathieu.desnoyers@efficios.com; dmarc=pass (policy=none) header.from=efficios.com; arc=pass ("microsoft.com:s=arcselector10001:i=1") ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1768312312; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=uNpDQG1AeQWl9vqmtBEpOwBdLB3//Ue4XMBS4qOWd2g=; b=D9QIXqnd3uwtqiBp8LUnXxNafVw/Z5+vMhHukp7u3skqgK5YT8LyimjszNqPR/RW6vfpOS acd39yAuQAtS5w6LNDkst2hFKW0f/k8E53SmKIPLMk26qlIg88j8y005+vOGODEY/hokGL gNyrlu+BOb6c4uB/0XX8EQjR1VbySDo= ARC-Authentication-Results: i=2; imf23.hostedemail.com; dkim=pass header.d=efficios.com header.s=selector1 header.b=CiSbhKYJ; spf=pass (imf23.hostedemail.com: domain of mathieu.desnoyers@efficios.com designates 52.101.191.122 as permitted sender) smtp.mailfrom=mathieu.desnoyers@efficios.com; dmarc=pass (policy=none) header.from=efficios.com; arc=pass ("microsoft.com:s=arcselector10001:i=1") ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1768312312; a=rsa-sha256; cv=pass; b=oDFU9T3BSm3riHMHvYdLUP1w8guC5fhzNl8Shb3thN5tgFiPHynbe430edjXLWyNfzp59e 13EZHREegblWGTSrxOCKwoS7cTCdTvWhKnsclsnvq+iJUwwqmjCqZJpCtM193t53URYyMD DAgkqk2boIWe9gkDsp27vkKV+4elSac= ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=kqhvcn+3nSfITEf+jG1ezM3xMJRfeJxnWQV4Pi4LUSC5ZrJ5Eq7wMKqMCqchfXQgLReWnosXEsrCiQ1Du+ZDKf3HxQ2T1ghqVULl2t1NTY4injd0xBkzb3CF0gLQoxWlmqzvUGU0HbBr7P/3Y9oMPUhvMjuKVfK6x6uV+apUT+j1ZO+a6SFZDUWsvPkT07fUx/F/bZSCJO8gwx7MF8UkU9fgbvY/KGpRSC7yI66eY47fTzf1S4D2RNkELhphvNJlcTxvaFPAZHoCwDvAgEK6aCNcx7Na8hRwnDHoj2f1khQlxkE6mjqWdq2tNNArPTAW5d7RLkYWsfR0dQbH7TjXDA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=uNpDQG1AeQWl9vqmtBEpOwBdLB3//Ue4XMBS4qOWd2g=; b=coUxqh1PRfK3cJvYf/H5RFp7fKtYo5Vr8xCVWP463/pLjUTHeJ265eVHSASBNrA+6BBOvmAHhAfR6kAhdKkYNkbBRf7NLslNN46SxOADPInkCTHtAc2P5yzUa5rjVmalJg7WsxutmpzlQoAdCwU/D1QNB/49DCxXj8t4dCrTWORillSdae/y0y8jYnzevhlKVemlMEJ7Ymuii0AfdPURH6MMt0wWi0fMMy9ogou6L9XZRjXefu9mJA9ljAixSfJi0susI9ZuB/vsmLh0PjpiL0AV0gsRAK7ceyF/oYM9HE1SNxjBQffqjw/Ul8nrnon91CWLqaOuYCn0FI1APwPPNg== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=efficios.com; dmarc=pass action=none header.from=efficios.com; dkim=pass header.d=efficios.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=efficios.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=uNpDQG1AeQWl9vqmtBEpOwBdLB3//Ue4XMBS4qOWd2g=; b=CiSbhKYJy/OCI7JF03VeFESUK7te5PCGrJSJCca4cdUo3A8fRrK1E9SmCDZy2fzGKqo6xyVfDEOJYYVT8CUbQfb9iGTJUKioyRfgxBWTeKwK5fi6wUbR06wOPdCX/rSoecEj3clFgNVDR1inPLvAKVvLMQuXI9rFeJ7NJhMI+n1qlE6i4q/sePlscsBVXMhdPcGMonatwaRtpcMMttjrK42eM7n1k9s70rFc5umEYSRHmqztkRWMWfQ8467BjV1toh+CrCyJpan8SZnSWf8WbEYwCJ0/UltRRIitpZ9FpnnxWxkPl4VAeFuVuc5GpgWJb0000PYNb78Fy7zdN1K+6Q== Received: from YT2PR01MB9175.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:b01:be::5) by YQBPR0101MB5441.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:c01:44::19) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9499.7; Tue, 13 Jan 2026 13:51:47 +0000 Received: from YT2PR01MB9175.CANPRD01.PROD.OUTLOOK.COM ([fe80::6004:a862:d45d:90c1]) by YT2PR01MB9175.CANPRD01.PROD.OUTLOOK.COM ([fe80::6004:a862:d45d:90c1%5]) with mapi id 15.20.9499.008; Tue, 13 Jan 2026 13:51:47 +0000 Message-ID: Date: Tue, 13 Jan 2026 08:51:45 -0500 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v13 2/3] mm: Fix OOM killer inaccuracy on large many-core systems To: Michal Hocko Cc: Andrew Morton , linux-kernel@vger.kernel.org, "Paul E. McKenney" , Steven Rostedt , Masami Hiramatsu , Dennis Zhou , Tejun Heo , Christoph Lameter , Martin Liu , David Rientjes , christian.koenig@amd.com, Shakeel Butt , SeongJae Park , Johannes Weiner , Sweet Tea Dorminy , Lorenzo Stoakes , "Liam R . Howlett" , Mike Rapoport , Suren Baghdasaryan , Vlastimil Babka , Christian Brauner , Wei Yang , David Hildenbrand , Miaohe Lin , Al Viro , linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org, Yu Zhao , Roman Gushchin , Mateusz Guzik , Matthew Wilcox , Baolin Wang , Aboorva Devarajan References: <20260111194958.1231477-1-mathieu.desnoyers@efficios.com> <20260111194958.1231477-3-mathieu.desnoyers@efficios.com> From: Mathieu Desnoyers Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: YQBPR0101CA0136.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:c01:e::9) To YT2PR01MB9175.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:b01:be::5) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: YT2PR01MB9175:EE_|YQBPR0101MB5441:EE_ X-MS-Office365-Filtering-Correlation-Id: 8490741c-aef9-4e7c-5466-08de52aae503 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|7416014|376014|1800799024; X-Microsoft-Antispam-Message-Info: =?utf-8?B?OUR5eTNGQjYxc05JY0NQZWJ3dkVuS0VFM0YvVzdBS3NtMFpDbHBYKy9oVGxJ?= =?utf-8?B?K1RvSzcwQVBKT0dpTEtyMFdzU2Y0UXFUNDZIbHNCa3BGVG9JYTh3Z1MxbE96?= =?utf-8?B?RlBoMmtGcmo2ajlVMkMrMFc3aThpRDhCUjRtZ0dUT043YkU1Mms0aTZ4NzJm?= =?utf-8?B?R1krVTFNb3psRzBJMnFBSGpBRWJ4K2NNMTZaREdBSnFvam5lbUt4bVNSa3N6?= =?utf-8?B?UmozVmFTVzJYREpPb2FFTDlNQVZodVhiOE5STDc3WStVdHBOUFdCNzNLenY0?= =?utf-8?B?OS91c2YwK283ZFRmY2VpTTNtWGNhbmdIYm1EbkFTTjUvYW82YWR1RDJGT0sz?= =?utf-8?B?aEpTM1lnTVpyQkdqWmc2WEZXSkpIV2xEdFhXbHUvR0IxNkgyQ09oMnRlSzlI?= =?utf-8?B?dnJIczE5NXRDeTFLQXZJd3RMdTNUQTU4dGlydjQxSmV1Z0VBUVdEVHMzTkNo?= =?utf-8?B?cUFacWlYdW9Sd3RKZUhzY2gvSjYrVzN1TTZOeS9uVEdhTy95NlRsVVNzSVRK?= =?utf-8?B?bjlOVFZmMUkxdXBzdE5vYWdzQ0VzK2hvSzRGNlRSWEU1YXc0ampaQ0djMExj?= =?utf-8?B?WVlyV3VLd0pYV0RpdjAvT0JRVk1HSW9VbXAvSUlNejF3Tm5LWmIvQ1ZFdW53?= =?utf-8?B?dmNoVFFxYUsvUGFNTjZLTGVHbFZtL0w5bXlHb0FlVjJ1WW9scFF3RW9FZW1W?= =?utf-8?B?K3NzTGtVdCsrR2dzZHNJY0NYYS9uTFMxRFdEOHVOeUlsU3Q1cjc3UkVwWW5L?= =?utf-8?B?V05wUnBsSm5NdHVXNStLdlJlUCtFVDE2c2VjcmZPdzNKa1pKc2RNUTN2Tyti?= =?utf-8?B?cVlkTHcyb3pNTGJFZS8vQWErRTVlMTNhTjlUVk5SaGlZVm9HcHluVVNTMDln?= =?utf-8?B?MldrVnRaWXRBUXJoZ2hzZU5iaWJhYXIwc05pT3JyY2JrSDB3NlpZbGppMlJa?= =?utf-8?B?eEo1em1TL013b2MzSDJLSExyZU16aEpDZjdLdC9WczFsU2p6YXl0U3EzQnZk?= =?utf-8?B?b2doaHVyS1cvM2xJLzM5bGZwUXp6WnA0dGJhMDltUS9va3U2TTRWSlZzbnZz?= =?utf-8?B?WHQ4dDNZRHVkZUVzUkxkQVRDd2JQM3hhYzRzNm41Um9paTlZMnE5WTd2Y2Vm?= =?utf-8?B?Y1J0cHNzWHR2UnI3VjZDeld5bVA3dkkvNFRtazFCSEpKTWNmTVRqWWVKcitt?= =?utf-8?B?c29ub2xrVnExNUg5VjNnVUJuQlhYai9lbjZadjNZVUh0S0hDVmJTS3kwTlhS?= =?utf-8?B?YXR5cUk0QWdzTDY3bnRlL1lnR2hHWW9aUCs4dzJKU2pXQlFQTDA0N3hiY2Fa?= =?utf-8?B?Wm1tNmdPemIrY3pqczBkbkNWU1ZFc1FnV28wOU03aStCbmp4bU1Nb3Z2SGVx?= =?utf-8?B?K2U3eEVGTDVINmVkTFlFNWo3TDdJWFZxMSswMDFvTG9QVEZIRC90cEhYVngw?= =?utf-8?B?WWIzc25rcEFmdkpHNnR2MExpeE94Vm5zTXJFRllFUTFYWXVxYXdaUUNuSFM4?= =?utf-8?B?dGhXTGxJNlcxNXFRQi9BMmNwOWJMUXpqT0ZTVmRFYmxhM1BCbkovbHFwMlBR?= =?utf-8?B?Wk93a0xINVZQR0tFWXFJZ2N5dlM4RFBjaDhXUHZ5dURRYmpJZWN3MUY0UExK?= =?utf-8?B?VUVzS0pZRDV2VFVXQ3ZhL0RTeEZVZ2FubnBVbTRhL3lPUnNtSS9lU0p1S0ZK?= =?utf-8?B?YjNmdHl2dHVTSjFNbnB4bnErWDYvcWZlMnlodTI3QVpudDhPbVVBSW0waEVs?= =?utf-8?B?Y1M5WnRVeEgvV2VpaGtoWEljUDg4RUtwbTRxRnZDMDRLeW9qbEkxMTBSYkox?= =?utf-8?B?a1ZUcm4wUUZXa1lCVXR5ZzQwNVRoR0F6dDl2emJ2Nm8xVWNLQUxUZjFLa3lN?= =?utf-8?B?YzhwYUZuWldjOGZuSENqSUNnTGJZVHB1dG5MeXdTclRFYUE9PQ==?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:YT2PR01MB9175.CANPRD01.PROD.OUTLOOK.COM;PTR:;CAT:NONE;SFS:(13230040)(366016)(7416014)(376014)(1800799024);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?dWxEdzlKcFJkR3lEeWl3ZnJpSUtaV1E5Uk9iU29sWTBtWHhJRWpOdk43dUxa?= =?utf-8?B?aStqU3V3VVJFL1JLYXAzUFZqZ2NmQ3YzRnRXUDkvNy9ZYnQ3and2U1hmdWNh?= =?utf-8?B?M2NUM054U3lIclNieGIxbFNmalk3dm9RUEoycDIyZThyMDZhb21rV0ZsdjY2?= =?utf-8?B?UkpMQUdTM2hwbHo0RzF6Uk5icnNYalZWV1hXMGhvOFYvTVM0cmFoQ29kc1Vj?= =?utf-8?B?LytrMitvRXBCN1NSbUlDcWVLU1l1ZUlJV3VKY2VqL29YcXZicWEwTGFsaW9k?= =?utf-8?B?b24yMVpWN3J1NWwyVk5sVVkyRDdnZHcwd1M5N1o5K3BlVUpCMnpvUDIxRnFa?= =?utf-8?B?VVpadk05cmxLcGFBMFVJamJ3SjFwVzg2ZUJla2tuSDkrZHRIK3g4dWVxcWRq?= =?utf-8?B?b0thdEQ1VVJvRitJeHZqL2l5TzR3c1hjRFFLcDJPcTcxYldNazRHeU9raGYx?= =?utf-8?B?dFUyNVQ4RzhnWDRwS1h1SkxWWm9lRlhJaGFNaUgzdFhQdisrWDQzek5zWEt0?= =?utf-8?B?VUhXazRDR3pKb1Bldi91Y21pT3pXUXgrVGhlNmhXN3hwK1dIc1RFVlBQZmNC?= =?utf-8?B?U3V2WFpOSlNDNWJCZEtYOGRncDgzNWN5dUdreXN1NUQ2N2xNMUZZaHJWY3NR?= =?utf-8?B?NTFYc2FBa1NBV2tQTmVRNzl5K0k0KzdIdXBsd3ZjV04rV0lwVVMyK1lSeFEr?= =?utf-8?B?eml0Y2JIQWxCOG0yTXdlZS9ocUpEdmtzR1VSaDNBbjRVZU04NnNhT2NRdm0z?= =?utf-8?B?d3RLbjhCOTY5UldZYmYvenc3eU5ORkZxNlZITUVaUHhURjdtK1g0ZTdTSWhE?= =?utf-8?B?VEJFeFlxVjdlSU9UdHU1YmY2QmU4eDc0dlVLa09xMEZ3SXV3YkVaZnlLd3Bo?= =?utf-8?B?MEduSXVjN29JdWNxWFhqd2ZyWHljdVoyVlpEYjFSOEtmZklGZU9PbFYyaU8w?= =?utf-8?B?WGZDZXZQVkR5Uk50ZVJ1VFJGSm5kdC9xeUlYMXQ1YWFIY2VzNUFCZjErWG1S?= =?utf-8?B?ZXRJWDVyaFlSbWZXWU1ZWVIvWnY2dGRtWnFqUG5UUEEvMmo5Q2VBQUhvMG9y?= =?utf-8?B?Y0NHRytQRys5c3FHMzNHSUhMVkdxNGJkT2NVd2I0ZEI4c0xOVFhaRjNHNGNE?= =?utf-8?B?bWd0MnREZ01Sa0gyTnp5VnF3K1doRm5WME1Bd1hYUC8zU2I0MDNaQnNhYmNK?= =?utf-8?B?ajhNdmNDaWxlUUZhN3hqMXdla3JHQktTN2p2U1A2aDFSYkpicVp5Zkt6dHRV?= =?utf-8?B?ajBiM3ZKL2lVYW14dVFCRVRuZisra3JjWm9VcHFraU94a0pyZDBkZlQ1dlE5?= =?utf-8?B?aTdoZGNtRTNXZEZBSGJ0TldSTjJIdldxWkZNQXE0ZFlyVW13eVBZTHBhTGRF?= =?utf-8?B?N281ekZtaUNCT3FPWnkwbDF0WUFnUVFYME42R05kMDU4WXYwUG1RdE45VVBv?= =?utf-8?B?SkxRekthc2diRHdLV0FuMmo3My9OQ2dnM0xQVDlXczViMzROZzVGTUxkNmxl?= =?utf-8?B?OXl6UllCNE43ZXpzZkMwNjVlTlRQS1FBNjBwNjY1RzFHaHJtdVJkQmlFRldN?= =?utf-8?B?M0hzK09zRWJtWTVReC9KYWt1cU42bXdycW1hWE9wVUYyd0dCUUhDRjhZNjkv?= =?utf-8?B?MjdQK0x6c1h5TEhVbkYxOHZrTTdxci93RTAxYjFPTEZ4Vld6TW9MVGw1cHRm?= =?utf-8?B?TlU2N29mZHJPNUxpdmphVDR1ZE5hRWxmWVRsZ3dXU25iRURieEhGd21QMlRa?= =?utf-8?B?MFdXN09CU1FJTURrd2JyVXpKRjVBOG5WZVN2emwyQUxHYklyTXFTN0p0TXEx?= =?utf-8?B?NnhROEZNZ3FNUFZhOVR3WWtLTjhnTHcwVHloWGlRNDBzbkxNaThlRFpIaWpw?= =?utf-8?B?RjBZUmdTYW1QbUFOVkc5N1JidmFXVFFuaExHS2JlbUQyNUdoakszMkY4V0hh?= =?utf-8?B?MXk4ZlVvNmU2YjQwOVFoNDRQUFdENXlFOHlZOC9ZK0VSRjFiRWh0eHhLQ3lu?= =?utf-8?B?dlRUUTVOTzRCL2pYTDRWRThhS3ZzelA5eFFScTNWQ1k2S21kMk1FRldrenh4?= =?utf-8?B?OTNNbHdUZTFSbGZsTDRUM1JKSDJ3bEpGMmZsWHJmbHQwOXBnZzlMODlDYzdk?= =?utf-8?B?KzExTlozL3lUbG1LZlE5cTREY2cweGE0a0VRbWo1dm9MNGJUTHJoSWc0YWdY?= =?utf-8?B?T2kzSFZYVUpJbkhmaFpOdWtaVmI4TW5EL1dtWWRFSDc2dTBYcjZrdnNTQkVY?= =?utf-8?B?Ui9sWmFGdFJCLzNpWjhEbm1aQ1AxY2diR1lHMHFKRUxLamFmRk9tUUN4UVNW?= =?utf-8?B?dkU4Y0ZVS0tYdVF0alpic0VuOFlMZkk0K1cxUTNiRmc4TTAzaHk4U29DaXky?= =?utf-8?Q?FMIOCKyvErQ6kd+U=3D?= X-OriginatorOrg: efficios.com X-MS-Exchange-CrossTenant-Network-Message-Id: 8490741c-aef9-4e7c-5466-08de52aae503 X-MS-Exchange-CrossTenant-AuthSource: YT2PR01MB9175.CANPRD01.PROD.OUTLOOK.COM X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 13 Jan 2026 13:51:47.4885 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 4f278736-4ab6-415c-957e-1f55336bd31e X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 3zBeHAsSNJj59n3UZbSVUJFpVhRhlt1JCB6x5LBSs0DuXkbnY68mCjFONDhmyJTDayJQf1SUDsTp1gVR+Ff3Adt7KgmRtAcrLZqji/E8UOI= X-MS-Exchange-Transport-CrossTenantHeadersStamped: YQBPR0101MB5441 X-Rspamd-Queue-Id: 6D16414000F X-Stat-Signature: rgprt156ti9sud9zftzw7r3h8uz71xg1 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1768312312-49176 X-HE-Meta: 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 pqGLLS52 j0iY4CtTL27WUix4WzuIKmALwjUnlZNMjDx+tggO38WcgF12b/U5g0xlR3/sHWO+dKQfIo0fR2tm/I0qCqQuiTDrSuYH4hA9VXqbgGkdyEBVGUr6cG9eVMLzuSMA8tGMpKU82QpSQX0iodg8DbXPBvtDqvsjH1rz8aimaUX8a253rhlbecsHhyLI7b6Xr/Kp81SPyNnsSnAX62yFw0klzvMWTXa8QsRP4TmTwqcS1axEjgaqZDEOOnzhaFk5TF0wmJFrChPTe7W2aaWnw9o5PdrNjRN1rnoDf/R6JEiWY4gdymtqvxUIZdxEpmgXfNC27TOBfLk1gkcQ3JohoxigOIWH8+m8Juv9zs7lAaJPDyT/FLd8Mlj7sGRpQ8pYmXkgluw4IPetxe4ncq7tpMUoUFNaEMBuTLyFgLlI6vi4vRFfZJeOUAhDgf0dGRP4gJyADuts3prHgUhM0VCd9AQyOxxdaMYjBvNzrAmUVmjvr+5oBd4zlEPDxInwofgpqkwd/KRsNd02DQAIlpD30rMkCv9KnqBEOUVWGwR6zuPajEILZ/cDtlzTQIKuqyumcr8hKIKVeXhrWJfFe6qs= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2026-01-13 04:24, Michal Hocko wrote: [...] >> Would you be OK with introducing changes in the following order ? >> >> 1) Fix the OOM killer inaccuracy by using counter sum (iteration on all >> cpu counters) in task selection. This may slow down the oom killer, >> but would at least fix its current inaccuracy issues. This could be >> backported to stable kernels. >> >> 2) Introduce the hierarchical percpu counters on top, as a oom killer >> task selection performance optimization (reduce latency of oom kill). >> >> This way, (2) becomes purely a performance optimization, so it's easy >> to bissect and revert if it causes issues. > > Yes, this makes more sense. > >> I agree that bringing a fix along with a performance optimization within >> a single commit makes it hard to backport to stable, and tricky to >> revert if it causes problems. >> >> As for finding other users of the hpcc, I have ideas, but not so much >> time available to try them out, as I'm pretty much doing this in my >> spare time. > > I do understand this constrain and motivation to have OOM situation > addressed with a priority. I am pretty sure that if you see issues in > OOM path then other consumers of get_mm_counter would be affected as > well. Namely /proc//stat. Indeed /proc//stat (implemented in fs/proc/array.c:do_task_stat()) uses get_mm_rss() which currently exports the approximated value to userspace. > There might be others but I can imagine > that some of them are more performance than precision sensitive. Agreed. > All that being said it seems that we need slow-and-precise and > fast-approximate interfaces to have incremental path for other users as > well. Looking at patch 1 it seems there are interfaces available for > that. I think it would be great to call those out explicitly in the > highlevel doc to give some guidance what to use when with what kind of > expectations. I figured I'd first focus on the oom killers internals before tackling the userspace ABI aspect of the problem, but since you're bringing it up, here is what I have in mind, more or less: - Introduce new proc files, e.g. /proc//rss/approximate /proc//rss/precise Where the "approximate" file would export the following lines for each page type (MM_FILEPAGES, MM_ANONPAGES, MM_SWAPENTS, MM_SHMPAGES, allowing future additions): And "precise" would export lines for each page type: The key thing here is to have different files to query approximated vs precise values, so we don't have the overhead of the precise sum when all we need is an approximation. This would expose all the bits and pieces needed to allow userspace to implement something similar to the 2-pass algorithm I'm proposing for the OOM killer, but tweaked for other use-cases. This proposed ABI is purely hypothetical at this stage. Please let me know if you have something different in mind. When you mention "highlevel doc", which document do you have in mind ? Something related to lib/percpu_counter_tree.c or to the /proc ABI ? Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. https://www.efficios.com