linux-kernel - Re: [PATCH 4/5] sched: Add rt task enqueue/dequeue trace points

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <767a9d59081220594d21856f329fb35988ef7925.camel@redhat.com>
Date: Wed, 30 Jul 2025 15:53:14 +0200
From: Gabriele Monaco <gmonaco@...hat.com>
To: Nam Cao <namcao@...utronix.de>, Steven Rostedt <rostedt@...dmis.org>, 
 Masami Hiramatsu <mhiramat@...nel.org>, Mathieu Desnoyers
 <mathieu.desnoyers@...icios.com>, 	linux-trace-kernel@...r.kernel.org,
 linux-kernel@...r.kernel.org
Cc: Ingo Molnar <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>, 
 Juri Lelli <juri.lelli@...hat.com>, Vincent Guittot
 <vincent.guittot@...aro.org>, Dietmar Eggemann	 <dietmar.eggemann@....com>,
 Ben Segall <bsegall@...gle.com>, Mel Gorman	 <mgorman@...e.de>, Valentin
 Schneider <vschneid@...hat.com>
Subject: Re: [PATCH 4/5] sched: Add rt task enqueue/dequeue trace points

On Wed, 2025-07-30 at 14:45 +0200, Nam Cao wrote:
> Add trace points into enqueue_task_rt() and dequeue_task_rt(). They
> are useful to implement RV monitor which validates RT scheduling.
> 

I get it's much simpler this way, but is it that different to follow
the task's existing tracepoints?

* task going to sleep (switch:prev_state != RUNNING) is dequeued
* task waking up is enqueued
* changing the tasks's policy (setpolicy and setattr syscalls) should
enqueue/dequeue as well

This is more thinking out loud, but I'm doing right now something
rather similar with the deadline tasks and this seems reasonable, at
least on paper.

What do you think?

Thanks,
Gabriele

> Signed-off-by: Nam Cao <namcao@...utronix.de>
> ---
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Juri Lelli <juri.lelli@...hat.com>
> Cc: Vincent Guittot <vincent.guittot@...aro.org>
> Cc: Dietmar Eggemann <dietmar.eggemann@....com>
> Cc: Ben Segall <bsegall@...gle.com>
> Cc: Mel Gorman <mgorman@...e.de>
> Cc: Valentin Schneider <vschneid@...hat.com>
> ---
>  include/trace/events/sched.h | 8 ++++++++
>  kernel/sched/rt.c            | 4 ++++
>  2 files changed, 12 insertions(+)
> 
> diff --git a/include/trace/events/sched.h
> b/include/trace/events/sched.h
> index c08893bde255..c38f12f7f903 100644
> --- a/include/trace/events/sched.h
> +++ b/include/trace/events/sched.h
> @@ -898,6 +898,14 @@ DECLARE_TRACE(sched_set_need_resched,
>  	TP_PROTO(struct task_struct *tsk, int cpu, int tif),
>  	TP_ARGS(tsk, cpu, tif));
>  
> +DECLARE_TRACE(enqueue_task_rt,
> +	TP_PROTO(int cpu, struct task_struct *task),
> +	TP_ARGS(cpu, task));
> +
> +DECLARE_TRACE(dequeue_task_rt,
> +	TP_PROTO(int cpu, struct task_struct *task),
> +	TP_ARGS(cpu, task));
> +
>  #endif /* _TRACE_SCHED_H */
>  
>  /* This part must be outside protection */
> diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
> index e40422c37033..f4d3f5e7fbec 100644
> --- a/kernel/sched/rt.c
> +++ b/kernel/sched/rt.c
> @@ -1480,6 +1480,8 @@ enqueue_task_rt(struct rq *rq, struct
> task_struct *p, int flags)
>  {
>  	struct sched_rt_entity *rt_se = &p->rt;
>  
> +	trace_enqueue_task_rt_tp(rq->cpu, p);
> +
>  	if (flags & ENQUEUE_WAKEUP)
>  		rt_se->timeout = 0;
>  
> @@ -1501,6 +1503,8 @@ static bool dequeue_task_rt(struct rq *rq,
> struct task_struct *p, int flags)
>  
>  	dequeue_pushable_task(rq, p);
>  
> +	trace_dequeue_task_rt_tp(rq->cpu, p);
> +
>  	return true;
>  }
>