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Thu, 9 Jul 2026 21:57:49 +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 v7 07/12] sched/debug: Add migration stats due to non preferred CPUs Date: Fri, 10 Jul 2026 03:26:43 +0530 Message-ID: <20260709215648.1246821-8-sshegde@linux.ibm.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260709215648.1246821-1-sshegde@linux.ibm.com> References: <20260709215648.1246821-1-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-GUID: KgVQvuIPTnqXkQramDLMYw8AeInfXGn7 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzA5MDIxOCBTYWx0ZWRfXw3i8RbQ5sGvB SIJnr1d74SQZtaFWm1sa/5srqlxZChKi0tznzygnNGOr1balIhq4yDhy6kNDb5Dt9Y00JuyLb0n YJ37J94Lo3OvCIS1iWkdlqBc1wuAh8RlJjDuAIfLSiMjRVqpx2OXlFQmemM34dGQ8s4+DzBK8m7 EEnE9nqmJPp6vej/vd2Uj1E173gq8uWtSqC1elYGsZx8sfobSJMXlcSF4Vj7+yIxC+pBaRNhPWN AvpBNQD4R45vB07J7Vo7ld5X1VsL8l+43MrV3PhxQ+ObzlSgXfnrtvN2GDgXRSLPPENdalAZwZ7 91PpO0XSYZ0U3NTlCr3kyZJSRIvlC2BYuPHLoUNE+YOlzZaEsjGqWpp0gN8KQc4nn3f6hmxVz8i THhV+O9Ro/xU86NbMqL7n0WkZmg/nCMwwUOPH8OrI3so0eb+jXz+z0R2rwUe0FWFUHov3Y5QF6o t3vwwnsEaloB20sjPgg== X-Proofpoint-ORIG-GUID: KIDFo0dyc-nu05P1MddBxc3X_wGcH_b2 X-Authority-Analysis: v=2.4 cv=FqQ1OWrq c=1 sm=1 tr=0 ts=6a50196b cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VnNF1IyMAAAA:8 a=-i9lZGrASMRMKgkbeRgA:9 X-Proofpoint-Spam-Info: AW1haW4tMjYwNzA5MDIxOCBTYWx0ZWRfX9MTfo8hacsLR grdQjBQYK2IA3e+pnU7zLnD3L7UWW6jYI3A3Cf06w+d+jEg+zrboUxKDeWeythlOWjxnsKjGK6b i3DgEJUmJ/WBwkeQMuSddn9ygrh2P94= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-09_04,2026-07-09_04,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 impostorscore=0 clxscore=1015 malwarescore=0 lowpriorityscore=0 priorityscore=1501 bulkscore=0 suspectscore=0 spamscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607090218 Add a new stat, - nr_migrations_cpu_non_preferred: number of migrations happened since a CPU was marked as non preferred due to high steal time. Signed-off-by: Shrikanth Hegde --- v6->v7: - Check if rq indeed changed or not before increment. include/linux/sched.h | 1 + kernel/sched/core.c | 10 ++++++++-- kernel/sched/debug.c | 1 + 3 files changed, 10 insertions(+), 2 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 968b18a7f470..37849d2f1dbd 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -554,6 +554,7 @@ struct sched_statistics { u64 nr_failed_migrations_running; u64 nr_failed_migrations_hot; u64 nr_forced_migrations; + u64 nr_migrations_cpu_non_preferred; u64 nr_wakeups; u64 nr_wakeups_sync; diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 74c93a88bf84..1ca1eefbdaf9 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -11324,8 +11324,14 @@ static int sched_non_preferred_cpu_push_stop(void *arg) context_unsafe_alias(rq); - if (task_rq(p) == rq && task_on_rq_queued(p)) - rq = __migrate_task(rq, &rf, p, cpu); + if (task_rq(p) == rq && task_on_rq_queued(p)) { + struct rq *dest_rq; + + dest_rq = __migrate_task(rq, &rf, p, cpu); + if (rq != dest_rq) + schedstat_inc(p->stats.nr_migrations_cpu_non_preferred); + rq = dest_rq; + } rq_unlock(rq, &rf); raw_spin_unlock_irq(&p->pi_lock); diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index 72236db67983..5ebb2055e6d5 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -1446,6 +1446,7 @@ void proc_sched_show_task(struct task_struct *p, struct pid_namespace *ns, P_SCHEDSTAT(nr_failed_migrations_running); P_SCHEDSTAT(nr_failed_migrations_hot); P_SCHEDSTAT(nr_forced_migrations); + P_SCHEDSTAT(nr_migrations_cpu_non_preferred); P_SCHEDSTAT(nr_wakeups); P_SCHEDSTAT(nr_wakeups_sync); P_SCHEDSTAT(nr_wakeups_migrate); -- 2.47.3