From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from SA9PR02CU001.outbound.protection.outlook.com (mail-southcentralusazon11013014.outbound.protection.outlook.com [40.93.196.14]) (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 6BC092820A9 for ; Wed, 6 May 2026 03:44:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=40.93.196.14 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778039043; cv=fail; b=SjMTMo6EHZEw+gEo9CMuGgJpp+h+Jf4G+OsXOHF9aogLK6zt9TfHEcgYTnza5tI7VpHYur8OMawf/YPfnMUFZsHvULARurIEujhR2Z7T3GyaGVsE0QqeQZBfQaIh+rTwFQHG7cD8iiK7O8SKz73m5hXhLtrNJ+wSXwZ7WRLeb1o= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778039043; c=relaxed/simple; bh=E8a3TAgO2n0v92kP5Zc503KO4rFSJg+84Jtnihb/vcE=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=hj+2pourbwdVqzm82AoLYl9Lwm4uK2YP9kZ67XuU1yNE1/1kO40jeoYP/obSjomhkEKoEL/eKh23bm0mV5nzfUMaJ/HttosavFlaBL0RdMeEGe0+oT3KjmznNMaTBQsa5R7cO116Q57KTislPQkkERa3pKz0fkbgY0zkBNkMfCE= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com; spf=fail smtp.mailfrom=amd.com; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b=uX6U7++h; arc=fail smtp.client-ip=40.93.196.14 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=amd.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b="uX6U7++h" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=TNZ6hh7XbfOGv2zOO6Rmx10xzdOIsagZ2SlOpxYlQOGRN64xijq0oZeFcZCfnJ+kHyTiw84C8hJaQwVrH/68RNb8/wz/CQP8CbRX5aDvSv1yaXEpkve2yNS4ACqlf8fcVi8NlbjRspyPxMmndL6lH+YD//cmakf3g4UhWBiOLNT7bWnrTZ7kp8UR7lNsddrJeRX4QTs/OIMXC7QWIvu6ytlK4e/agggC3ASez+RsAuk95RMfHVBEap83aigsR+y2P/VNnH5W/NR49TfX0Fwl8EMKx0PQi+06aUHjVZ1QDP+Ux5A0bG7TCTtABaseESlv5w6XNwWW3L2Mx+UTJdDOzw== 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=pPTmQe+denm0Js6sbmuPxiand0WvyQuCmvVCiSeyhac=; b=vj9dPfWSpKU5ObneDn5GetMsDywrLxmCPmlKDQ6NydUIEF4zunXqNjZodhSt/SSiV3vUNW97Ni2Cw56NrSGnAfBGKm+QGeXu+Sehod+BjcGzARrA6K4XGKqVA6zllnLmUH7S2M/hCJMQCVbbcTGj0QzAsmHN6nPleWFS0BuVJbb1XWTjPXyCJCuoa8+SbtAo8Y5S2HKm3lOj2zZp4OvQW8gOjQaCDH/pKc9P69fUPx41KyAC6RKzdF6eUFSmvoHmImA3TAk1bzCQNqhvYh7kj85brKEB/Xz3m/YrOy0qBAviXMSmDEx2r94LM6+XSY+AlDBihF+I4emOCd3LIg0MuQ== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass (sender ip is 165.204.84.17) smtp.rcpttodomain=nvidia.com smtp.mailfrom=amd.com; dmarc=pass (p=quarantine sp=quarantine pct=100) action=none header.from=amd.com; dkim=none (message not signed); arc=none (0) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amd.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=pPTmQe+denm0Js6sbmuPxiand0WvyQuCmvVCiSeyhac=; b=uX6U7++hMnQFx2nGrdvhMCfnbT7V1BO7Mk3pWmSNsjL2MGUi4O9W4ENvqbXSdL+djQtG5j9HSX7Yb81HOYUt5H7WrDbLYuylYeBrm5Cl/qU3q58nRSbU3AF7eroKK7Y8m9XftemOELgaj5mCZtGeanik6HC7li/5Uc6d8DkKnvc= Received: from BL1PR13CA0305.namprd13.prod.outlook.com (2603:10b6:208:2c1::10) by DM4PR12MB5723.namprd12.prod.outlook.com (2603:10b6:8:5e::9) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9870.27; Wed, 6 May 2026 03:43:56 +0000 Received: from BL6PEPF0001AB4F.namprd04.prod.outlook.com (2603:10b6:208:2c1:cafe::8c) by BL1PR13CA0305.outlook.office365.com (2603:10b6:208:2c1::10) with Microsoft SMTP Server (version=TLS1_3, cipher=TLS_AES_256_GCM_SHA384) id 15.20.9891.14 via Frontend Transport; Wed, 6 May 2026 03:43:56 +0000 X-MS-Exchange-Authentication-Results: spf=pass (sender IP is 165.204.84.17) smtp.mailfrom=amd.com; dkim=none (message not signed) header.d=none;dmarc=pass action=none header.from=amd.com; Received-SPF: Pass (protection.outlook.com: domain of amd.com designates 165.204.84.17 as permitted sender) receiver=protection.outlook.com; client-ip=165.204.84.17; helo=satlexmb08.amd.com; pr=C Received: from satlexmb08.amd.com (165.204.84.17) by BL6PEPF0001AB4F.mail.protection.outlook.com (10.167.242.73) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9891.9 via Frontend Transport; Wed, 6 May 2026 03:43:55 +0000 Received: from satlexmb10.amd.com (10.181.42.219) by satlexmb08.amd.com (10.181.42.217) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.17; Tue, 5 May 2026 22:43:55 -0500 Received: from satlexmb07.amd.com (10.181.42.216) by satlexmb10.amd.com (10.181.42.219) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.17; Tue, 5 May 2026 22:43:55 -0500 Received: from [10.252.223.214] (10.180.168.240) by satlexmb07.amd.com (10.181.42.216) with Microsoft SMTP Server id 15.2.2562.17 via Frontend Transport; Tue, 5 May 2026 22:43:48 -0500 Message-ID: <211a37f8-92a4-4e5a-9d55-b61b25f504a7@amd.com> Date: Wed, 6 May 2026 09:13:42 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v7 0/7] mm: Hot page tracking and promotion infrastructure To: Balbir Singh , Matthew Wilcox CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , References: <20260504060924.344313-1-bharata@amd.com> Content-Language: en-US From: Bharata B Rao In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BL6PEPF0001AB4F:EE_|DM4PR12MB5723:EE_ X-MS-Office365-Filtering-Correlation-Id: ced88d0b-4dde-4213-eba0-08deab21b2ea X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|82310400026|1800799024|376014|7416014|36860700016|13003099007|18002099003|56012099003|22082099003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:satlexmb08.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(82310400026)(1800799024)(376014)(7416014)(36860700016)(13003099007)(18002099003)(56012099003)(22082099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: wSXnWURpAWuBBUFbgFifXli5x/Por5S30fhpkAfhdTcp0qGESE8MosC7AvcR76pXQzbOQetZARWzkB/4n8TLMecrWEigs4pQ+6HAXN6/QDyMSHm4TDN+XD/5zlYraby6aQQx4etIs3hJ/eEKmDTS2lKJ+okL2ap0SYt9bTWy/RAHjow1ajbCH6I2xYivYHotpwq9HbU4HfH+ycMTzC5lX5a1kuWTCb16tOsLgN5l4HMcmeGtlmOZwWExAkn8jOIstWi0Av5sYVgf0PDqq780g9vhxbsCWMHdpdrRel+1UaAPzveftrZ2daQnlrvtcytVQjSVeZkbH+bvOTNDA1MBs+fAPc0pL0PCkLi7Q+oTmE4tl2d24iNj1aTiurdN2Ry0/pt2rgji9sF6D4jpiTngwO7ZCWc5uiPVT4pdTg1g2t5MerPlP+C5N3l3xVIE0Yl5 X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 06 May 2026 03:43:55.6665 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: ced88d0b-4dde-4213-eba0-08deab21b2ea X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb08.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BL6PEPF0001AB4F.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR12MB5723 On 06-May-26 3:47 AM, Balbir Singh wrote: > On 5/5/26 06:36, Matthew Wilcox wrote: >> On Mon, May 04, 2026 at 11:39:17AM +0530, Bharata B Rao wrote: >>> This is v7 of pghot, a hot-page tracking and promotion subsystem. The >> >> I continue to think we should not do this. >> > > I am unclear about the benefits of the patchset, I have not tested > it or reviewed the latest revision. My big concern was that top-tier > might not always be suitable. So you are saying that we should have a capability to promote accessed pages from lower tier to an other tier that is not classified as top tier? Is that non-top tier node the one which generates accesses? > > I see that there are some numbers posted, but I find this weird > "After the graph creation, the processes are stopped and data is migrated > to CXL node 2 before continuing so that BFS phase starts accessing lower > tier memory." Why not allocate everything on CXL node 2? In the ideal scenario, the benefit is to see if any pages that land up on lower tier get identified as hot and get promoted. That means we need to create an over-committed scenario where the pages get demoted first. I have provided numbers from such cases in my previous versions. The problem with this case is that the base hot page promotion (NUMAB2) hasn't shown any benefit at all with my micro-benchmark - Ref: https://lore.kernel.org/linux-mm/868004d8-bb8e-4800-9fdd-ade48e95fe3b@amd.com/ Same has been observed with redis-memtier benchmark - https://lore.kernel.org/linux-mm/957f2242-56d4-4bf0-8aeb-9d60fbea8c8c@amd.com/ Instead what I am doing here is to take out demotion from the scenario but still retain the access pattern of the benchmark by pushing out the data to lower tier when the benchmark reaches steady allocation state. Regards, Bharata.