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Tue, 7 Apr 2026 19:20:51 +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, tglx@linutronix.de, yury.norov@gmail.com, gregkh@linuxfoundation.org Cc: sshegde@linux.ibm.com, pbonzini@redhat.com, seanjc@google.com, kprateek.nayak@amd.com, vschneid@redhat.com, iii@linux.ibm.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, joelagnelf@nvidia.com Subject: [PATCH v2 09/17] sched/core: Keep tick on non-preferred CPUs until tasks are out Date: Wed, 8 Apr 2026 00:49:42 +0530 Message-ID: <20260407191950.643549-10-sshegde@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260407191950.643549-1-sshegde@linux.ibm.com> References: <20260407191950.643549-1-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-Authority-Analysis: v=2.4 cv=KeridwYD c=1 sm=1 tr=0 ts=69d5591d cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=A5OVakUREuEA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VnNF1IyMAAAA:8 a=QWx9vYyWXuU5Gb4Iy2kA:9 X-Proofpoint-ORIG-GUID: qEgJLgENmTrLqYKwtj5dbCcw3l9s9oiB X-Proofpoint-GUID: Poo27fxu2Zl4fmhOZJQHLbomG8T3IX8C X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDA3MDE3NSBTYWx0ZWRfX4jlOE+Bj54O7 4iNil0bKUfwFAI6CGUoYk32xbIagj2nKP9T2F1HmfPXPnAoUblKVtrg0Rv76xa+pxLJQuHLoapw vD3qBsqUnL6q9aX+gp+TRAtBfgxNfAUI2Da6oBcFYAb86PAepuiJTEtM1gLj+RvC5NawQ5tjtSH kEiftpHU/LLkbSGR2UGJi/ZvVvbJJz3+86y+tTNIom+lBolRhr+gy3D6genFKOYl9a/TVuHF2Yw hNzbr5Ky24Wwg1X1AeiE/tBhmmDQf5K36l7y2OqcEaTbRuVlTYcGcMSBx07bTqjyTl/IxIMS/1l ViMIwCIO3cbAHM1Rw0tc3p5nFq/xLkMbED5hx0xCK2fY85Tvu4tVZNk0Fy4HFwQmD2lyF+L6uUS BxKBRqD/NBVMdHuwF247dLCdZmXymZN9yc1Jb9W/Pcns44dWuGgCYtwmZU+qIlXkHWPUOqQKyI4 isJ4mCUo55zsYi55Ydg== 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=2026-04-07_04,2026-04-07_05,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 malwarescore=0 lowpriorityscore=0 adultscore=0 impostorscore=0 clxscore=1015 phishscore=0 priorityscore=1501 spamscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604010000 definitions=main-2604070175 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 336e7c694eb7..c7f046443dc5 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1407,6 +1407,10 @@ 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