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Tue, 27 Jan 2026 01:10:49 -0800 (PST) Received: from [127.0.0.1] ([176.33.57.146]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4804db63817sm129522665e9.3.2026.01.27.01.10.47 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 27 Jan 2026 01:10:48 -0800 (PST) Date: Tue, 27 Jan 2026 09:10:46 +0000 From: Gabriele Monaco To: Peter Zijlstra Cc: K Prateek Nayak , Tomas Glozar , Clark Williams , John Kacur , linux-trace-kernel@vger.kernel.org, Ingo Molnar , Nam Cao , Steven Rostedt , linux-kernel@vger.kernel.org, Juri Lelli Message-ID: <8883042e-49b4-4cba-b0f8-d12e4cfa3d6c@redhat.com> In-Reply-To: <20260122155500.362683-10-gmonaco@redhat.com> References: <20260122155500.362683-1-gmonaco@redhat.com> <20260122155500.362683-10-gmonaco@redhat.com> Subject: Re: [PATCH v5 09/15] sched: Add task enqueue/dequeue trace points Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Correlation-ID: <8883042e-49b4-4cba-b0f8-d12e4cfa3d6c@redhat.com> 2026-01-22T15:56:08Z Gabriele Monaco : > From: Nam Cao > > Add trace points into enqueue_task() and dequeue_task(). > Peter, can I have your Ack on this? (Apologies for the spam, I sent it as HTML by mistake) Thanks, Gabriele > Suggested-by: Peter Zijlstra > Signed-off-by: Nam Cao > Reviewed-by: K Prateek Nayak > Signed-off-by: Gabriele Monaco > --- > > Notes: > =C2=A0=C2=A0=C2=A0 V5: > =C2=A0=C2=A0=C2=A0 * Do not fire enqueue tracepoint for delayed enqueues > > include/trace/events/sched.h | 13 +++++++++++++ > kernel/sched/core.c=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= | 10 +++++++++- > kernel/sched/sched.h=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 |=C2= =A0 2 ++ > 3 files changed, 24 insertions(+), 1 deletion(-) > > diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h > index 366b2e8ec40c..f4e1d3554e3e 100644 > --- a/include/trace/events/sched.h > +++ b/include/trace/events/sched.h > @@ -912,6 +912,19 @@ DECLARE_TRACE(sched_dl_server_stop, > =C2=A0=C2=A0=C2=A0 TP_PROTO(struct sched_dl_entity *dl_se, int cpu), > =C2=A0=C2=A0=C2=A0 TP_ARGS(dl_se, cpu)); > > +/* > + * The two trace points below may not work as expected for fair tasks du= e > + * to delayed dequeue. See: > + * https://lore.kernel.org/lkml/179674c6-f82a-4718-ace2-67b5e672fdee@amd= .com/ > + */ > +DECLARE_TRACE(sched_enqueue, > +=C2=A0=C2=A0 TP_PROTO(struct task_struct *tsk, int cpu), > +=C2=A0=C2=A0 TP_ARGS(tsk, cpu)); > + > +DECLARE_TRACE(sched_dequeue, > +=C2=A0=C2=A0 TP_PROTO(struct task_struct *tsk, int cpu), > +=C2=A0=C2=A0 TP_ARGS(tsk, cpu)); > + > #endif /* _TRACE_SCHED_H */ > > /* This part must be outside protection */ > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index f6293fa02fb7..c885d7885172 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -2087,6 +2087,9 @@ unsigned long get_wchan(struct task_struct *p) > > void enqueue_task(struct rq *rq, struct task_struct *p, int flags) > { > +=C2=A0=C2=A0 if (trace_sched_enqueue_tp_enabled() && !(flags & ENQUEUE_D= ELAYED)) > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 trace_sched_enqueue_tp(p, rq->cpu); > + > =C2=A0=C2=A0=C2=A0 if (!(flags & ENQUEUE_NOCLOCK)) > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 update_rq_clock(rq); > > @@ -2114,6 +2117,8 @@ void enqueue_task(struct rq *rq, struct task_struct= *p, int flags) > =C2=A0 */ > inline bool dequeue_task(struct rq *rq, struct task_struct *p, int flags) > { > +=C2=A0=C2=A0 int ret; > + > =C2=A0=C2=A0=C2=A0 if (sched_core_enabled(rq)) > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 sched_core_dequeue(rq, p, flag= s); > > @@ -2131,7 +2136,10 @@ inline bool dequeue_task(struct rq *rq, struct tas= k_struct *p, int flags) > =C2=A0=C2=A0=C2=A0=C2=A0 */ > =C2=A0=C2=A0=C2=A0 uclamp_rq_dec(rq, p); > =C2=A0=C2=A0=C2=A0 rq->queue_mask |=3D p->sched_class->queue_mask; > -=C2=A0=C2=A0 return p->sched_class->dequeue_task(rq, p, flags); > +=C2=A0=C2=A0 ret =3D p->sched_class->dequeue_task(rq, p, flags); > +=C2=A0=C2=A0 if (trace_sched_dequeue_tp_enabled() && !(flags & DEQUEUE_S= LEEP)) > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 trace_sched_dequeue_tp(p, rq->cpu); > +=C2=A0=C2=A0 return ret; > } > > void activate_task(struct rq *rq, struct task_struct *p, int flags) > diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h > index e885a935b716..8465472b40fa 100644 > --- a/kernel/sched/sched.h > +++ b/kernel/sched/sched.h > @@ -2918,6 +2918,8 @@ static inline void sub_nr_running(struct rq *rq, un= signed count) > > static inline void __block_task(struct rq *rq, struct task_struct *p) > { > +=C2=A0=C2=A0 trace_sched_dequeue_tp(p, rq->cpu); > + > =C2=A0=C2=A0=C2=A0 if (p->sched_contributes_to_load) > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 rq->nr_uninterruptible++; > > -- > 2.52.0