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Wed, 19 Nov 2025 12:45:20 +0000 (GMT) From: Shrikanth Hegde To: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Cc: sshegde@linux.ibm.com, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, tglx@linutronix.de, yury.norov@gmail.com, maddy@linux.ibm.com, srikar@linux.ibm.com, gregkh@linuxfoundation.org, 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, christophe.leroy@csgroup.eu Subject: [PATCH 06/17] sched/fair: Pass current cpu in select_idle_sibling Date: Wed, 19 Nov 2025 18:14:38 +0530 Message-ID: <20251119124449.1149616-7-sshegde@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251119124449.1149616-1-sshegde@linux.ibm.com> References: <20251119124449.1149616-1-sshegde@linux.ibm.com> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: HAkR2ikVxu5ppvG9Ed_Za4Od8QKMpVeP X-Authority-Analysis: v=2.4 cv=Rv3I7SmK c=1 sm=1 tr=0 ts=691dbbea cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=6UeiqGixMTsA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VnNF1IyMAAAA:8 a=LR1EqIGjcEKtFJDgD-kA:9 X-Proofpoint-GUID: pARDVr-xXswqWRaIiOxPaFZZUMaQYkp4 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMTE1MDAzMiBTYWx0ZWRfX0Qm17IMWwbLJ v8hZM/dV4NL8xBKpRBtWnHBFe6Zn3ob4/BKPmlEe0EuI6FgDFdX2xAAeroIBBdeJ29mfAMxv0AA sVCHtHVeSs1oC8n1Qim0kYNwLy1AQR6V0F3Ern8BSFv+Zjy0sMDtrd2HWH4HDnq55QV5nXX8jYt M4UR7IY/d1k3Pf0bEhTY+/ExQTlKZXRYeVbNQwr9fgRItEAoRXBMCht+PVFtbZAyrMOBPatcGaI RcPMH3rdQHiXKZjeI2AF0CgbA5cdNsQdYB9R3TQHqf0fiRQo1MFhmJ+lFcK+JZk1BvBn0YehOtu 19oxSJDrpvb9HDtikueMLajv2+Lj3MFfk0zh3POZa9xWlQwcGDDmUt8qvSkDREfeV0INTPgWL/4 N69X83IJ/LvRrWrvZyu+GfgivX37Hg== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2025-11-19_03,2025-11-18_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 suspectscore=0 clxscore=1015 phishscore=0 priorityscore=1501 spamscore=0 lowpriorityscore=0 impostorscore=0 adultscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2510240000 definitions=main-2511150032 Pattern in select_task_rq_fair: cpu = smp_processor_id(); new_cpu = prev_cpu; //May change new_cpu due to wake_affine, otherwise it remains prev_cpu new_cpu = select_idle_sibling(p, prev_cpu, new_cpu); Due to this often prev_cpu == new_cpu. If the task was sleeping when the prev_cpu was marked as paravirt, it would be beneficial to choose current cpu instead. If the current cpu is paravirt too, then wakeup will happen there and at next tick task will move out. So pass current CPU as well in the select_idle_sibling. Signed-off-by: Shrikanth Hegde --- kernel/sched/fair.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 1855975b8248..015e00b370c9 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1048,7 +1048,7 @@ static bool update_deadline(struct cfs_rq *cfs_rq, struct sched_entity *se) #include "pelt.h" -static int select_idle_sibling(struct task_struct *p, int prev_cpu, int cpu); +static int select_idle_sibling(struct task_struct *p, int this_cpu, int prev, int target); static unsigned long task_h_load(struct task_struct *p); static unsigned long capacity_of(int cpu); @@ -7770,7 +7770,7 @@ static inline bool asym_fits_cpu(unsigned long util, /* * Try and locate an idle core/thread in the LLC cache domain. */ -static int select_idle_sibling(struct task_struct *p, int prev, int target) +static int select_idle_sibling(struct task_struct *p, int this_cpu, int prev, int target) { bool has_idle_core = false; struct sched_domain *sd; @@ -8578,7 +8578,7 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int wake_flags) new_cpu = sched_balance_find_dst_cpu(sd, p, cpu, prev_cpu, sd_flag); } else if (wake_flags & WF_TTWU) { /* XXX always ? */ /* Fast path */ - new_cpu = select_idle_sibling(p, prev_cpu, new_cpu); + new_cpu = select_idle_sibling(p, cpu, prev_cpu, new_cpu); } rcu_read_unlock(); -- 2.47.3