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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=satlexmb07.amd.com; pr=C Received: from satlexmb07.amd.com (165.204.84.17) by BN6PEPF00000073.mail.protection.outlook.com (10.167.248.200) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.451.8 via Frontend Transport; Thu, 24 Sep 2026 06:26:12 +0000 Received: from satlexmb07.amd.com (10.181.42.216) by satlexmb07.amd.com (10.181.42.216) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.49; Thu, 24 Sep 2026 01:26:11 -0500 Received: from [192.168.0.152] (10.180.168.240) by satlexmb07.amd.com (10.181.42.216) with Microsoft SMTP Server id 15.2.2562.49 via Frontend Transport; Thu, 24 Sep 2026 01:26:03 -0500 Message-ID: <736ed7a4-3eed-445a-9838-37558bab8bc6@amd.com> Date: Thu, 24 Sep 2026 11:56:02 +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: [RFC PATCH v0 0/3] pghot: x86: IBS Memory Profiler for hot page promotion To: , CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , References: <20260924062206.319314-1-bharata@amd.com> Content-Language: en-US From: Bharata B Rao In-Reply-To: <20260924062206.319314-1-bharata@amd.com> Content-Type: text/plain; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: mcCnP5/juDmkCvngY8N3egF1AERh5LVh8kaGECLGFTEBJuUW9HLaCagl+4El/DaVz7efEYVfMEZTu5nfbTrqCIPeEJlkOuKfuR+/FS1KsHBQhQqUuL1F0XTm6i6uRgQG+AQ9EJFHrRx88t7qx/Shss2shx+pxriJxHqrqwNS4sDzzz/4xeDcHdJIDuyzaCN+Bkq911W0H6+b1jB+iuOAN8M0Wg+hkcp5B2FJB3CaMzgkbMzSlJTY2Ws9F++xRVZeR5bBmsqJzJ7nMHdFczlXpWQHw+jG1JZUwchn6L52vGwNxmZBQMA/VL+g5ZpehZzUBMua+3G2+xSadKzJ14oVSu0LtnA3L96oVXG3rGsiaAN7iBzRBhkPDGMW+XudZKRXzlTRuQEb1QOrOq+T9B6YDyJKCTA+XsLcs72ymcjIPIQI5HDMG7xgFYmja2M8xoaf X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 24 Sep 2026 06:26:12.2851 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 78d82c9f-120c-4cc9-9944-08df1a04baa1 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=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BN6PEPF00000073.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY8PR12MB7194 On 24-Sep-26 11:52 AM, Bharata B Rao wrote: > > Detailed per-benchmark tables (throughput/latency + vmstat and pghot > promotion counters) are posted as replies to this thread. Micro-benchmark Multi-threaded application with 64 threads that access memory(8G) at 4K granularity repetitively and randomly. The number of accesses per thread and the randomness pattern for each thread are fixed beforehand. The accesses are divided into stores and loads in the ratio of 50:50. Benchmark threads run on Node 0, while memory is initially provisioned on CXL node 2 before the accesses start. Repetitive accesses results in lowertier pages becoming hot and kmigrated detecting and migrating them. The benchmark score is the time taken to finish the accesses in microseconds. The sooner it finishes the better it is. All the numbers shown below are average of 3 runs. Table 1: Completion time (lower is better), avg of 3 runs 64 threads, random 4K access over 8G, mem on CXL node 2, cpu node 0 Config Time (us) Time (s) Speedup --------------------------------------- C1 98,485,716 98.5 1.00x C2 38,636,402 38.6 2.55x C3 44,270,350 44.3 2.22x Speedup = C1 (base-NUMAB0) time / config time (>1.00x is faster) Legend: C1 = base kernel, NUMAB0 (hot page promotion disabled) C2 = base kernel, NUMAB2 (hot page promotion enabled) C3 = pghot kernel, IBS profiler, pghot_freq_threshold=1 (NUMAB0) Table 2: Page migration / hotness vmstat counters (avg of 3 runs) '-' = counter not present for that kernel/config vmstat counter C1 C2 C3 ------------------------------------------------------------ pgpromote_success 0 2,097,152 1,981,045 pgpromote_candidate_nrl 0 2,412,042 1,981,045 numa_pages_migrated 0 2,097,152 1,981,045 numa_pte_updates 0 2,097,152 0 numa_hint_faults 0 2,412,042 0 pghot_recorded_accesses - - 1,985,269 pghot_reported_hintfaults - - 0 pghot_reported_hwhints - - 5,991,177 hwhint_total_events - - 5,991,177 hwhint_dram_accesses - - 3,716,462 hwhint_extmem_accesses - - 1,886,078 hwhint_cache_accesses - - 0 hwhint_useful_events - - 5,991,177 hwhint_dropped_events - - 0 Legend: C1 = base kernel, NUMAB0 (hot page promotion disabled) C2 = base kernel, NUMAB2 (hot page promotion enabled) C3 = pghot kernel, IBS profiler, pghot_freq_threshold=1 (NUMAB0)