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Wed, 17 Jun 2026 17:43:31 +0000 (GMT) Received: from li-7bb28a4c-2dab-11b2-a85c-887b5c60d769.ibm.com.com (unknown [9.39.28.77]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 17 Jun 2026 17:43:31 +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 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, mgorman@suse.de, bsegall@google.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 Subject: [PATCH v4 09/20] sched/core: Keep tick on non-preferred CPUs until tasks are out Date: Wed, 17 Jun 2026 23:11:28 +0530 Message-ID: <20260617174139.155540-10-sshegde@linux.ibm.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260617174139.155540-1-sshegde@linux.ibm.com> References: <20260617174139.155540-1-sshegde@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@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-Proofpoint-Spam-Info: AW1haW4tMjYwNjE3MDE2NiBTYWx0ZWRfX+4la5RFwMTfj LO9jHedFXGXcRQYokRE/Huyh9yotNeC+AC/NFUVrRErGMuwgPQYB/xSmzuseTFVfx433fdawdit QPWcKmKdSdNEWeE8MGMSY8hFODiV24o= X-Proofpoint-GUID: w2MyqWBl8sT10V85wvu43cTIqPuFC95A X-Authority-Analysis: v=2.4 cv=bMgm5v+Z c=1 sm=1 tr=0 ts=6a32dcd0 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=FelO9ux0wxsA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VnNF1IyMAAAA:8 a=QWx9vYyWXuU5Gb4Iy2kA:9 X-Proofpoint-ORIG-GUID: Fp-7ZmAdyi9xn5aC_UUa7YKPsWk0r1TN X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNjE3MDE2NiBTYWx0ZWRfXyEoHNrsZGw3B oeOKNlkovY3aS8/jYkTN6OAlmgoa1ZYJL3Qus2DNF2oCokOygrfzim6H7MwfSI5L426BYSCm3O4 A/JHZ65rIuzxG60qASDYe715KlG7W2no3bebnjomJUsguMoUFj0TOJ2GxWX6WwIUKBIGeztPsb4 o7Etzo6D28+nKgpeYcqk8LT4JPtky66ZepxHQAE/4HtqQh5TC/Qn8m1x76x33xEFdSDKXg8QoLL Fg5AnOBaigUY6s9LlOq01BrXzjCq39yggvRL0J1eZecFdDiRTcqfAga/9ak2Gl5Wrq0bk+kN/R7 iBf0rVtGGFrxfZrZxVrLnemtpOhmBjWHGRNKoZ/igUKqd22I59JR+6Xyl1xBdL2Lg0AcyqmSNF0 TWcBuhiQeZXHvozeBR096VGD0yVtjLbbp20Nr+71RL25SIqnVr033yaM7xAdfJ1jbTA48/hL72/ kO+Cy8H+OH4ApWf2gyQ== 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=2026-06-17_02,2026-06-17_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 impostorscore=0 malwarescore=0 adultscore=0 spamscore=0 bulkscore=0 priorityscore=1501 phishscore=0 clxscore=1015 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2606170166 Enable tick on nohz full CPU when it is marked as non-preferred. If there in no CFS 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 714816cfa975..390a4de28b3c 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1431,6 +1431,10 @@ bool sched_can_stop_tick(struct rq *rq) if (rq->dl.dl_nr_running) return false; + /* Keep the tick running until CFS tasks are pushed out*/ + if (!cpu_preferred(rq->cpu) && rq->cfs.h_nr_queued) + return false; + /* * If there are more than one RR tasks, we need the tick to affect the * actual RR behaviour. -- 2.47.3