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client-ip=165.204.84.17; helo=satlexmb08.amd.com; pr=C Received: from satlexmb08.amd.com (165.204.84.17) by DS1PEPF00017091.mail.protection.outlook.com (10.167.17.133) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9564.3 via Frontend Transport; Wed, 28 Jan 2026 03:06:04 +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, 27 Jan 2026 21:06:03 -0600 Received: from satlexmb08.amd.com (10.181.42.217) 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, 27 Jan 2026 21:06:03 -0600 Received: from [10.136.38.16] (10.180.168.240) by satlexmb08.amd.com (10.181.42.217) with Microsoft SMTP Server id 15.2.2562.17 via Frontend Transport; Tue, 27 Jan 2026 21:05:59 -0600 Message-ID: <5e001aeb-50a8-475f-bff2-6d101e15d078@amd.com> Date: Wed, 28 Jan 2026 08:35:58 +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] sched/clock: Avoid false sharing for sched_clock_irqtime To: "Guo, Wangyang" , Shrikanth Hegde CC: , Benjamin Lei , "Tim Chen" , Tianyou Li , "Ingo Molnar" , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider References: <20260127072509.2627346-1-wangyang.guo@intel.com> <7c6236a5-82b7-4d1b-9bb2-3f0d2ac186f8@linux.ibm.com> <3b69443c-f82c-4b73-8384-2a039d730213@intel.com> Content-Language: en-US From: K Prateek Nayak In-Reply-To: <3b69443c-f82c-4b73-8384-2a039d730213@intel.com> Content-Type: text/plain; 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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 28 Jan 2026 03:06:04.0514 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 4ec27668-efd4-4706-44e6-08de5e1a2c72 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: DS1PEPF00017091.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA1PR12MB9246 On 1/28/2026 7:49 AM, Guo, Wangyang wrote: > Yes, when clock mark unstable through tsc_.*mark_unstable() with non-native_sched_clock, clear_sched_clock_stable won't be called, thus sched_clock_irqtime still keep enabled. > > Maybe the dedicated workqueue for sched_clock_irqtime is still needed considering this case. In that case, shouldn't tsc_init() only enable irqtime when using_native_sched_clock()? How can tsc_init() make a call on irqtime if TSC isn't being used as the sched_clock() ultimately? For kvmclock, if PVCLOCK_TSC_STABLE_BIT is not set, it'll call clear_sched_clock_stable() at kvm_sched_clock_init() but none of the other clocksources do so we can assume once we override the sched_clock() it is up to the sched_clock() provider to deal with the clock stability. -- Thanks and Regards, Prateek