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client-ip=165.204.84.17; helo=satlexmb07.amd.com; pr=C Received: from satlexmb07.amd.com (165.204.84.17) by CH1PEPF0000A345.mail.protection.outlook.com (10.167.244.8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9137.12 via Frontend Transport; Fri, 19 Sep 2025 03:54:06 +0000 Received: from satlexmb10.amd.com (10.181.42.219) 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 15.2.2562.17; Thu, 18 Sep 2025 20:54:05 -0700 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; Thu, 18 Sep 2025 20:54:04 -0700 Received: from [10.136.41.20] (10.180.168.240) by satlexmb08.amd.com (10.181.42.217) with Microsoft SMTP Server id 15.2.2562.17 via Frontend Transport; Thu, 18 Sep 2025 20:54:00 -0700 Message-ID: <7c827f3d-b9ed-48f7-bd61-98a128db81e7@amd.com> Date: Fri, 19 Sep 2025 09:23:59 +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 1/8] sched: Fix hrtick() vs scheduling context To: Peter Zijlstra , CC: , , , , , , , , , , , , , , References: <20250918075219.091828500@infradead.org> <20250918080205.442967033@infradead.org> Content-Language: en-US From: K Prateek Nayak In-Reply-To: <20250918080205.442967033@infradead.org> Content-Type: text/plain; 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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 19 Sep 2025 03:54:06.6012 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: d16e14c7-d65f-4609-2632-08ddf7302e78 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: CH1PEPF0000A345.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW4PR12MB6875 Hello Peter, On 9/18/2025 1:22 PM, Peter Zijlstra wrote: > The sched_class::task_tick() method is called on the donor > sched_class, and sched_tick() hands it rq->donor as argument, which is > consistent. > > However, while hrtick() uses the donor sched_class, it then passes > rq->curr, which is inconsistent. Fix it. Can we add either a: Fixes: 7de9d4f94638 ("sched: Start blocked_on chain processing in find_proxy_task()") where this starts making a difference functionally since single CPU proxy can have rq->curr != rq->donor, or we can target the same commit where task_tick(0 in sched_tick() was updated with: Fixes: af0c8b2bf67b ("sched: Split scheduler and execution contexts") Other than that, this looks good to me. Feel free to include: Reviewed-by: K Prateek Nayak > > Signed-off-by: Peter Zijlstra (Intel) > --- > kernel/sched/core.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -875,7 +875,7 @@ static enum hrtimer_restart hrtick(struc > > rq_lock(rq, &rf); > update_rq_clock(rq); > - rq->donor->sched_class->task_tick(rq, rq->curr, 1); > + rq->donor->sched_class->task_tick(rq, rq->donor, 1); > rq_unlock(rq, &rf); > > return HRTIMER_NORESTART; > > > -- Thanks and Regards, Prateek