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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 CO1PEPF000075EE.mail.protection.outlook.com (10.167.249.37) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.71.7 via Frontend Transport; Tue, 26 May 2026 10:54:38 +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 15.2.2562.41; Tue, 26 May 2026 05:54:37 -0500 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 15.2.2562.41; Tue, 26 May 2026 05:54:37 -0500 Received: from [172.31.184.125] (10.180.168.240) by satlexmb08.amd.com (10.181.42.217) with Microsoft SMTP Server id 15.2.2562.41 via Frontend Transport; Tue, 26 May 2026 05:54:33 -0500 Message-ID: <3f1fc681-a73b-4bd2-9a6a-e61b8fbd5826@amd.com> Date: Tue, 26 May 2026 16:24:32 +0530 Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 10/10] sched/eevdf: Move to a single runqueue To: Peter Zijlstra CC: Zhang Qiao , , , , , , , , , , , , , , , , , , Hui Tang References: <20260511113104.563854162@infradead.org> <20260511120628.206700041@infradead.org> <85116808-8643-47d7-b4e7-2a11c3999b20@amd.com> <20260526095210.GC4149641@noisy.programming.kicks-ass.net> Content-Language: en-US From: K Prateek Nayak In-Reply-To: <20260526095210.GC4149641@noisy.programming.kicks-ass.net> Content-Type: text/plain; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: qy9CmgqypM9iAXrOnRV+86MNZObknHyiVDCHJZpA8+4aqQM8lp+EFRf0cvaNHO5lIHExKi+Yt+blSfTHkbxCxy/30cpht6rmlk6l7rY5yOX0OZFpCcvsamESwDVfwfSRgt9+mxPa/bxP+n6mpRnWBWpCH03uY+oBtDra/echIm7LnwZngHCj7oPODo9NxWDnf0Fb2q0ru4w9MrMiBzKs1GiFheGlwKQL/xI17sxIcV+MUJ8aeJwQA2ZTwJ3xN3Ig9WC8Xy07H4r6ZpFSh1+9KKFT+Ig/2dqYZNwAS7MqX2CXaChqMYQ+NV/kWXznFpIe9EF/Zdm53KGEzRxjfQGXNlD3vpccRV+pqqvGA6mc8BHN7Z/Cy11JnlE+7elb6VMn2YvPert+Bbmzrfe71SGz7fr7k3kIf2xVxoIf8Ix+NvKnnzlvPgxOIsPN/BPSjF32 X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 26 May 2026 10:54:38.5929 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: ec886c06-798b-40e0-8a08-08debb152ecf 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: CO1PEPF000075EE.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH7PR12MB7257 Hello Peter, On 5/26/2026 3:22 PM, Peter Zijlstra wrote: > On Tue, May 26, 2026 at 02:45:45PM +0530, K Prateek Nayak wrote: > >> The suggested diff above solves the crash in my case but your >> mileage may vary. Peter can comment if this is the right thing >> to do or not :-) > > Is this a different issue than the one you raised before? Yes, this is different. Essentially, this is what is happening: throttle_cfs_rq_work() task_rq_lock() dequeue_task_fair(current) /* Task is dequeued on cfs side */ __dequeue_task(current) dequeue_hierarchy(current); current->se.on_rq = 0; /* update_load_sub() */ resched_curr(); /* Initiates a resched */ task_rq_unlock() local_irq_enable(); =====> sched_tick() task_tick_fair() __calc_prop_weight() /* * Oops: update_load_sub() above has * 0ed the weight of cfs_rq. */ <==== preempt_schedule_irq() next = ... put_prev_set_next_task() /* The runtime context is switched here */ > We talked about throtte, and you were going to make a proper patch of that cleanup > iirc. I had rebased your suggestion on tip and fixed a couple of splats but once it was functional, I noticed hackbench taking twice as long to complete compared to tip and I was chasing that before I fell sick. Let me go dig deeper to see where exactly it is all going sideways. -- Thanks and Regards, Prateek