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Thu, 14 May 2026 15:24:15 +0000 (GMT) Received: from li-7bb28a4c-2dab-11b2-a85c-887b5c60d769.ibm.com.com (unknown [9.124.213.185]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 14 May 2026 15:24:15 +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 v3 10/20] sched/core: Keep tick on non-preferred CPUs until tasks are out Date: Thu, 14 May 2026 20:51:54 +0530 Message-ID: <20260514152204.481115-11-sshegde@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260514152204.481115-1-sshegde@linux.ibm.com> References: <20260514152204.481115-1-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-Details-Enc: AW1haW4tMjYwNTE0MDE1MyBTYWx0ZWRfX2R6QYtiXu7cx 6PSbmZtMjMQ0KKwsft61NgFsJi49Dq8GJfcVVA//Bo3cFq/ATeC+3+zAJkvLp5ErMaHYYOwkgeC 3YwU3TFmi6hOiSXSu8aAt+oi4UjP05tBG25undYKHHgk7A+Gc2tP+pnbOmfhh++6DrPw3PgL+Qv pbK2FRHW3udLIvBevXmRGIzLKGtWRBmc9hvrJ8akxy+6H96Niuo3N8TwmybS3ZU+wRVnyemk4QL 8lPFcbGzn8f1WMT7kxWxcJ9SSwUDRgR6YK7D2GGHAxEGefOBHBigh1moZbr6QLZquMxKATLi9Tx uxNWKbvkpZ3VSKHn11g97VdvtPWP5UhUz6ArlyL7cO4dpCBYo+09eenWY9EE38VQ8Dl0DJ7dR76 SdDRLdYKK2Pr5kHK9d+OB3yQxXBLE9Ki2C8OU67bFC+ewp5XAm+FnoDhTP1yQdIQRPtdSF0OO2p mfgIA7ONUQ/ogl8Csvg== X-Proofpoint-ORIG-GUID: apwbAT36qg0xZdX8eV9aXCRV2gF2s6mZ X-Authority-Analysis: v=2.4 cv=Jc6Ma0KV c=1 sm=1 tr=0 ts=6a05e92d cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VnNF1IyMAAAA:8 a=QWx9vYyWXuU5Gb4Iy2kA:9 X-Proofpoint-GUID: nmh802J1SknqAxEXRQDCQNtv0Qgv0xNf X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-14_03,2026-05-13_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 priorityscore=1501 malwarescore=0 bulkscore=0 clxscore=1015 phishscore=0 adultscore=0 lowpriorityscore=0 suspectscore=0 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605050000 definitions=main-2605140153 Enable tick on nohz full CPU when it is marked as non-preferred. If there in no CFS/RT 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 292d4e7db0fd..86fa4bfaead0 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1420,6 +1420,10 @@ bool sched_can_stop_tick(struct rq *rq) if (rq->dl.dl_nr_running) return false; + /* Keep the tick running until both RT and CFS are pushed out*/ + if (!cpu_preferred(rq->cpu) && (rq->rt.rt_nr_running || 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