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Tue, 12 Aug 2025 23:50:44 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGuShnNGJ7nGbvS9Hkfc1PmPGBF5ZFOBaHg2Zh9sPeWe34ZfQ7UBXLn3E+cyFDkg+ZnNoAHvg== X-Received: by 2002:a05:622a:408d:b0:4b0:7f93:3cdb with SMTP id d75a77b69052e-4b0fc8c724bmr22314821cf.43.1755067843757; Tue, 12 Aug 2025 23:50:43 -0700 (PDT) Received: from gmonaco-thinkpadt14gen3.rmtit.csb ([185.107.56.42]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-4b07611dc5asm126034001cf.42.2025.08.12.23.50.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 12 Aug 2025 23:50:43 -0700 (PDT) Message-ID: <61d904e5dc673d398c20bc4359e0f9b16ef4fde4.camel@redhat.com> Subject: Re: [PATCH v3 4/5] sched: Add task enqueue/dequeue trace points From: Gabriele Monaco To: Ingo Molnar , Peter Zijlstra , Nam Cao , Steven Rostedt , linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Juri Lelli , Vincent Guittot , Masami Hiramatsu , Mathieu Desnoyers , Dietmar Eggemann , Ben Segall , Mel Gorman , Valentin Schneider , K Prateek Nayak Date: Wed, 13 Aug 2025 08:50:39 +0200 In-Reply-To: <918fe0f29a94e49db05c4f63a8a210dda9b90925.1754900299.git.namcao@linutronix.de> References: <918fe0f29a94e49db05c4f63a8a210dda9b90925.1754900299.git.namcao@linutronix.de> Autocrypt: addr=gmonaco@redhat.com; prefer-encrypt=mutual; keydata=mDMEZuK5YxYJKwYBBAHaRw8BAQdAmJ3dM9Sz6/Hodu33Qrf8QH2bNeNbOikqYtxWFLVm0 1a0JEdhYnJpZWxlIE1vbmFjbyA8Z21vbmFjb0ByZWRoYXQuY29tPoiZBBMWCgBBFiEEysoR+AuB3R Zwp6j270psSVh4TfIFAmbiuWMCGwMFCQWjmoAFCwkIBwICIgIGFQoJCAsCBBYCAwECHgcCF4AACgk Q70psSVh4TfJzZgD/TXjnqCyqaZH/Y2w+YVbvm93WX2eqBqiVZ6VEjTuGNs8A/iPrKbzdWC7AicnK xyhmqeUWOzFx5P43S1E1dhsrLWgP Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.56.2 (3.56.2-1.fc42) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Mon, 2025-08-11 at 10:40 +0200, Nam Cao wrote: > Add trace points into enqueue_task() and dequeue_task(). They are > useful to implement RV monitor which validates RT scheduling. >=20 > Signed-off-by: Nam Cao > --- Peter, Ingo, this patch adds new tracepoints in the scheduler do agree with the change, can we get an Ack? Thanks, Gabriele > Cc: Ingo Molnar > Cc: Peter Zijlstra > Cc: Juri Lelli > Cc: Vincent Guittot > Cc: Dietmar Eggemann > Cc: Ben Segall > Cc: Mel Gorman > Cc: Valentin Schneider > Cc: K Prateek Nayak > --- > v3: fix up build issue on !SMP > v2: Move the tracepoints to cover all task enqueue/dequeue, not just > RT > --- > =C2=A0include/trace/events/sched.h | 13 +++++++++++++ > =C2=A0kernel/sched/core.c=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0 |=C2=A0 8 +++++++- > =C2=A02 files changed, 20 insertions(+), 1 deletion(-) >=20 > diff --git a/include/trace/events/sched.h > b/include/trace/events/sched.h > index 7b2645b50e78..696d22af5a98 100644 > --- a/include/trace/events/sched.h > +++ b/include/trace/events/sched.h > @@ -896,6 +896,19 @@ DECLARE_TRACE(sched_set_need_resched, > =C2=A0 TP_PROTO(struct task_struct *tsk, int cpu, int tif), > =C2=A0 TP_ARGS(tsk, cpu, tif)); > =C2=A0 > +/* > + * The two trace points below may not work as expected for fair > tasks due > + * to delayed dequeue. See: > + * > https://lore.kernel.org/lkml/179674c6-f82a-4718-ace2-67b5e672fdee@amd.com= / > + */ > +DECLARE_TRACE(enqueue_task, > + TP_PROTO(int cpu, struct task_struct *task), > + TP_ARGS(cpu, task)); > + > +DECLARE_TRACE(dequeue_task, > + TP_PROTO(int cpu, struct task_struct *task), > + TP_ARGS(cpu, task)); > + > =C2=A0#endif /* _TRACE_SCHED_H */ > =C2=A0 > =C2=A0/* This part must be outside protection */ > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index be00629f0ba4..6367799aa023 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -2077,6 +2077,8 @@ unsigned long get_wchan(struct task_struct *p) > =C2=A0 > =C2=A0void enqueue_task(struct rq *rq, struct task_struct *p, int flags) > =C2=A0{ > + trace_enqueue_task_tp(cpu_of(rq), p); > + > =C2=A0 if (!(flags & ENQUEUE_NOCLOCK)) > =C2=A0 update_rq_clock(rq); > =C2=A0 > @@ -2119,7 +2121,11 @@ inline bool dequeue_task(struct rq *rq, struct > task_struct *p, int flags) > =C2=A0 * and mark the task ->sched_delayed. > =C2=A0 */ > =C2=A0 uclamp_rq_dec(rq, p); > - return p->sched_class->dequeue_task(rq, p, flags); > + if (p->sched_class->dequeue_task(rq, p, flags)) { > + trace_dequeue_task_tp(cpu_of(rq), p); > + return true; > + } > + return false; > =C2=A0} > =C2=A0 > =C2=A0void activate_task(struct rq *rq, struct task_struct *p, int flags)