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Thu, 31 Jul 2025 01:39:28 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFlb7Q8yPGsqPrhTD0Y5orBknXFGcVgXJ65AHafvMuaqJXp4tRD1gmzSipBYjnC3cMeTlLrew== X-Received: by 2002:adf:8b59:0:b0:3a6:d95e:f38c with SMTP id ffacd0b85a97d-3b79501e606mr3552988f8f.33.1753951167972; Thu, 31 Jul 2025 01:39:27 -0700 (PDT) Received: from gmonaco-thinkpadt14gen3.rmtit.csb ([185.107.56.40]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3b79c3b9c7dsm1589327f8f.26.2025.07.31.01.39.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 31 Jul 2025 01:39:27 -0700 (PDT) Message-ID: <5a7c492bbad7d56f347ee629734fdbab275d6333.camel@redhat.com> Subject: Re: [PATCH 4/5] sched: Add rt task enqueue/dequeue trace points From: Gabriele Monaco To: Nam Cao Cc: Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org, Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Ben Segall , Mel Gorman , Valentin Schneider Date: Thu, 31 Jul 2025 10:39:25 +0200 In-Reply-To: <20250731073520.ktIOaGts@linutronix.de> References: <8f83869a5040bd7cd3096bd12090c1ab110ae5c4.1753879295.git.namcao@linutronix.de> <767a9d59081220594d21856f329fb35988ef7925.camel@redhat.com> <20250730151818.7RemAREO@linutronix.de> <5065c29035be39dee954f2b233a40ae15dcc5035.camel@redhat.com> <20250731073520.ktIOaGts@linutronix.de> Autocrypt: addr=gmonaco@redhat.com; prefer-encrypt=mutual; keydata=mDMEZuK5YxYJKwYBBAHaRw8BAQdAmJ3dM9Sz6/Hodu33Qrf8QH2bNeNbOikqYtxWFLVm0 1a0JEdhYnJpZWxlIE1vbmFjbyA8Z21vbmFjb0ByZWRoYXQuY29tPoiZBBMWCgBBFiEEysoR+AuB3R Zwp6j270psSVh4TfIFAmbiuWMCGwMFCQWjmoAFCwkIBwICIgIGFQoJCAsCBBYCAwECHgcCF4AACgk Q70psSVh4TfJzZgD/TXjnqCyqaZH/Y2w+YVbvm93WX2eqBqiVZ6VEjTuGNs8A/iPrKbzdWC7AicnK xyhmqeUWOzFx5P43S1E1dhsrLWgP User-Agent: Evolution 3.56.2 (3.56.2-1.fc42) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: hvGVWajqEO0DlffRT5AwEyFcMIPvOBxyLhAyMjFAI3s_1753951168 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, 2025-07-31 at 09:35 +0200, Nam Cao wrote: > On Wed, Jul 30, 2025 at 06:18:45PM +0200, Gabriele Monaco wrote: > > Well, thinking about it again, these tracepoints might simplify > > things > > considerably when tasks change policy.. > >=20 > > Syscalls may fail, for that you could register to sys_exit and > > check > > the return value, but at that point the policy changed already, so > > you > > cannot tell if it's a relevant event or not (e.g. same policy). > > Also sched_setscheduler_nocheck would be out of the picture here, > > not > > sure how recurrent that is though (and might not matter if you only > > focus on userspace tasks). > >=20 > > If you go down the route of adding tracepoints, why not have other > > classes benefit too? I believe calling them from the enqueue_task / > > dequeue_task in sched/core.c would allow you to easily filter out > > by > > policy anyway (haven't tested). >=20 > Something like the untested patch below? >=20 > Will you have a use case for it too? Then I will try to accommodate > your use case, otherwise I will do just enough for my case. Well, I'm still defining the best set of tracepoints I need, if you see it cleaner go ahead the way you're currently doing, then. Unless anyone else complains let's keep it like this. Thanks, Gabriele >=20 > Nam >=20 > diff --git a/include/trace/events/sched.h > b/include/trace/events/sched.h > index c38f12f7f903..b50668052f99 100644 > --- a/include/trace/events/sched.h > +++ b/include/trace/events/sched.h > @@ -906,6 +906,14 @@ DECLARE_TRACE(dequeue_task_rt, > =C2=A0=09TP_PROTO(int cpu, struct task_struct *task), > =C2=A0=09TP_ARGS(cpu, task)); > =C2=A0 > +DECLARE_TRACE(enqueue_task, > +=09TP_PROTO(int cpu, struct task_struct *task), > +=09TP_ARGS(cpu, task)); > + > +DECLARE_TRACE(dequeue_task, > +=09TP_PROTO(int cpu, struct task_struct *task), > +=09TP_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 b485e0639616..2af90532982a 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{ > +=09trace_enqueue_task_tp(rq->cpu, p); > + > =C2=A0=09if (!(flags & ENQUEUE_NOCLOCK)) > =C2=A0=09=09update_rq_clock(rq); > =C2=A0 > @@ -2103,6 +2105,8 @@ void enqueue_task(struct rq *rq, struct > task_struct *p, int flags) > =C2=A0 */ > =C2=A0inline bool dequeue_task(struct rq *rq, struct task_struct *p, int > flags) > =C2=A0{ > +=09trace_dequeue_task_tp(rq->cpu, p); > + > =C2=A0=09if (sched_core_enabled(rq)) > =C2=A0=09=09sched_core_dequeue(rq, p, flags); > =C2=A0