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Wed, 1 Jul 2026 14:18:52 +0000 (GMT) From: Shrikanth Hegde To: linux-kernel@vger.kernel.org, mingo@kernel.org, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, yury.norov@gmail.com, kprateek.nayak@amd.com, iii@linux.ibm.com, corbet@lwn.net Cc: sshegde@linux.ibm.com, tglx@kernel.org, gregkh@linuxfoundation.org, pbonzini@redhat.com, seanjc@google.com, vschneid@redhat.com, huschle@linux.ibm.com, rostedt@goodmis.org, dietmar.eggemann@arm.com, maddy@linux.ibm.com, srikar@linux.ibm.com, hdanton@sina.com, chleroy@kernel.org, vineeth@bitbyteword.org, frederic@kernel.org, arighi@nvidia.com, pauld@redhat.com, christian.loehle@arm.com, tj@kernel.org, tommaso.cucinotta@gmail.com, maz@kernel.org, rafael@kernel.org, rdunlap@infradead.org, kernellwp@gmail.com, linux-doc@vger.kernel.org Subject: [PATCH v6 08/23] sched/core: Keep tick on non-preferred CPUs until tasks are out Date: Wed, 1 Jul 2026 19:46:39 +0530 Message-ID: <20260701141654.500125-9-sshegde@linux.ibm.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260701141654.500125-1-sshegde@linux.ibm.com> References: <20260701141654.500125-1-sshegde@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=a4kAM0SF c=1 sm=1 tr=0 ts=6a4521df cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VnNF1IyMAAAA:8 a=QWx9vYyWXuU5Gb4Iy2kA:9 X-Proofpoint-ORIG-GUID: KsnwIWiTColC7iK_oLtqnKKgewv2uhX6 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzAxMDE1MCBTYWx0ZWRfXzfXqdX7acTnb fcP+MF6hOlYkoFWKlYTWFtxeSNj56pgnKKWj6wQ/68mwbuVwkldiBqH94c4ZArBKIdlxY5SfINA zOOz94yERu6nn5bPG2cqEO24GUtCMsbu7J0DaxuhuqQ8tWKKWwgPDbLg8xupBhdsmcnZ+8UgTX/ H9LPtjIqrMkWxK7/kG042MGK9BAxkDSl18ONU93ESWs+s/F1+w5YJlNMYqqzkG0al2/QEAn34/O vxSu5kxC9XsWYiYqxgNJXY1KSxcT61F2l4zpAz6XIS/E9xP/Yqs/S6qWgQ46gWpWiPwZ9MwtQpF cxiFm2BUM64eECQJ7gtt/hhHZrHAWCoJmhwWxQ7auNqDQjpZoVtw8yW4HSypzmE4HVp/q0WvsDe X3oKe08sjzrcBWuYGKZLgM22siQBKHfXVYN6WD0gU1yrRYm32FRT5rSJ7G5Ba2BbW+rCfxPJdFF B4kpPEi0FmerPWjWoZw== X-Proofpoint-GUID: gvNwXb9LB1FGhnKhsxZ8w7vgavJb_mDo X-Proofpoint-Spam-Info: AW1haW4tMjYwNzAxMDE1MCBTYWx0ZWRfX3uVdO4bAjfqY jrtZXXzyqCeCYt2015a9ICDwj0LckJoyMu7fa/AxUBGPrsk3MgwQnHUpgk8YZWs07ydCYu1fjYK TMUwJRjfGsVi86szEvMO6sluqJpkYBE= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-07-01_03,2026-06-26_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 bulkscore=0 suspectscore=0 lowpriorityscore=0 impostorscore=0 spamscore=0 priorityscore=1501 adultscore=0 malwarescore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607010150 Enable tick on nohz full CPU when it is marked as non-preferred. If there in no FAIR task running there,disable the tick to save the power. Steal time handling code will call tick_nohz_dep_set_cpu with TICK_DEP_BIT_SCHED for moving the task out of nohz_full CPU fast. Signed-off-by: Shrikanth Hegde --- kernel/sched/core.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 1fb1c17e8387..aa4201bb8082 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1473,6 +1473,10 @@ bool sched_can_stop_tick(struct rq *rq) return false; } + /* Keep the tick running until CFS tasks are pushed out*/ + if (!cpu_preferred(rq->cpu) && rq->cfs.h_nr_queued) + return false; + return true; } #endif /* CONFIG_NO_HZ_FULL */ -- 2.47.3