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client-ip=165.204.84.17; helo=SATLEXMB04.amd.com; pr=C Received: from SATLEXMB04.amd.com (165.204.84.17) by DS2PEPF0000343C.mail.protection.outlook.com (10.167.18.39) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.8207.12 via Frontend Transport; Fri, 29 Nov 2024 18:26:20 +0000 Received: from [10.252.205.52] (10.180.168.240) by SATLEXMB04.amd.com (10.181.40.145) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.39; Fri, 29 Nov 2024 12:26:15 -0600 Message-ID: Date: Fri, 29 Nov 2024 23:56:12 +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 09/10 v2] sched/fair: Fix sched_can_stop_tick() for fair tasks To: Vincent Guittot , , , , , , , , , CC: , , , Tejun Heo , David Vernet References: <20241129161756.3081386-1-vincent.guittot@linaro.org> <20241129161756.3081386-10-vincent.guittot@linaro.org> Content-Language: en-US From: K Prateek Nayak In-Reply-To: <20241129161756.3081386-10-vincent.guittot@linaro.org> Content-Type: text/plain; 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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 29 Nov 2024 18:26:20.9908 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 275296d3-4a6d-47a4-8de7-08dd10a352c7 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=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: DS2PEPF0000343C.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ0PR12MB7081 (+ Tejun, David) Hello Vincent, On 11/29/2024 9:47 PM, Vincent Guittot wrote: > We can't stop the tick of a rq if there are at least 2 tasks enqueued in > the whole hierarchy and not only at the root cfs rq. > > rq->cfs.nr_queued tracks the number of sched_entity at one level > whereas rq->cfs.h_nr_enqueued tracks all enqueued tasks in the > hierarchy. > > Signed-off-by: Vincent Guittot > --- > kernel/sched/core.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 3571f91d4b0d..866a1605656c 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -1341,7 +1341,7 @@ bool sched_can_stop_tick(struct rq *rq) > if (scx_enabled() && !scx_can_stop_tick(rq)) > return false; > > - if (rq->cfs.nr_queued > 1) > + if (rq->cfs.h_nr_queued > 1) Perhaps we can move this fix to the beginning of the series and add: Fixes: 11cc374f4643b ("sched_ext: Simplify scx_can_stop_tick() invocation in sched_can_stop_tick()") before converting the h_nr_running to h_nr_queued since prior to that commit, sched_can_stop_tick() used to check "rq->nr_running" and since we check the count of DL, RR, and FIFO tasks up above, it would have captured number of fair tasks running before sched-ext. That way the fix can be backported easily to LTS too. Thoughts? > return false; > > /* -- Thanks and Regards, Prateek