linux-kernel - Re: [PATCH v3 09/13] sched: Add deadline tracepoints

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Message-ID: <20251205134130.GB400972@pauld.westford.csb>
Date: Fri, 5 Dec 2025 08:41:30 -0500
From: Phil Auld <pauld@...hat.com>
To: Gabriele Monaco <gmonaco@...hat.com>
Cc: linux-kernel@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>,
	Nam Cao <namcao@...utronix.de>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	linux-trace-kernel@...r.kernel.org,
	Tomas Glozar <tglozar@...hat.com>, Juri Lelli <jlelli@...hat.com>,
	Clark Williams <williams@...hat.com>,
	John Kacur <jkacur@...hat.com>
Subject: Re: [PATCH v3 09/13] sched: Add deadline tracepoints

On Fri, Dec 05, 2025 at 02:16:17PM +0100 Gabriele Monaco wrote:
> Add the following tracepoints:
> 
> * sched_dl_throttle(dl_se, cpu):
>     Called when a deadline entity is throttled
> * sched_dl_replenish(dl_se, cpu):
>     Called when a deadline entity's runtime is replenished
> * sched_dl_server_start(dl_se, cpu):
>     Called when a deadline server is started
> * sched_dl_server_stop(dl_se, cpu):
>     Called when a deadline server is stopped
> 
> Those tracepoints can be useful to validate the deadline scheduler with
> RV and are not exported to tracefs.
> 
> Signed-off-by: Gabriele Monaco <gmonaco@...hat.com>

These seem like they might be useful outside of the RV context as well.

Reviewed-by: Phil Auld <pauld@...hat.com>


Cheers,
Phil

> ---
> 
> Notes:
>     V3:
>     * Rename dl argument to dl_se in tracepoints
> 
>  include/trace/events/sched.h | 16 ++++++++++++++++
>  kernel/sched/core.c          |  4 ++++
>  kernel/sched/deadline.c      |  7 +++++++
>  3 files changed, 27 insertions(+)
> 
> diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
> index 7b2645b50e78..366b2e8ec40c 100644
> --- a/include/trace/events/sched.h
> +++ b/include/trace/events/sched.h
> @@ -896,6 +896,22 @@ DECLARE_TRACE(sched_set_need_resched,
>  	TP_PROTO(struct task_struct *tsk, int cpu, int tif),
>  	TP_ARGS(tsk, cpu, tif));
>  
> +DECLARE_TRACE(sched_dl_throttle,
> +	TP_PROTO(struct sched_dl_entity *dl_se, int cpu),
> +	TP_ARGS(dl_se, cpu));
> +
> +DECLARE_TRACE(sched_dl_replenish,
> +	TP_PROTO(struct sched_dl_entity *dl_se, int cpu),
> +	TP_ARGS(dl_se, cpu));
> +
> +DECLARE_TRACE(sched_dl_server_start,
> +	TP_PROTO(struct sched_dl_entity *dl_se, int cpu),
> +	TP_ARGS(dl_se, cpu));
> +
> +DECLARE_TRACE(sched_dl_server_stop,
> +	TP_PROTO(struct sched_dl_entity *dl_se, int cpu),
> +	TP_ARGS(dl_se, cpu));
> +
>  #endif /* _TRACE_SCHED_H */
>  
>  /* This part must be outside protection */
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 5516778c19eb..3aed0ed6f2e9 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -122,6 +122,10 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(sched_compute_energy_tp);
>  EXPORT_TRACEPOINT_SYMBOL_GPL(sched_entry_tp);
>  EXPORT_TRACEPOINT_SYMBOL_GPL(sched_exit_tp);
>  EXPORT_TRACEPOINT_SYMBOL_GPL(sched_set_need_resched_tp);
> +EXPORT_TRACEPOINT_SYMBOL_GPL(sched_dl_throttle_tp);
> +EXPORT_TRACEPOINT_SYMBOL_GPL(sched_dl_replenish_tp);
> +EXPORT_TRACEPOINT_SYMBOL_GPL(sched_dl_server_start_tp);
> +EXPORT_TRACEPOINT_SYMBOL_GPL(sched_dl_server_stop_tp);
>  
>  DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
>  DEFINE_PER_CPU(struct rnd_state, sched_rnd_state);
> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
> index 319439fe1870..2192e9f42e02 100644
> --- a/kernel/sched/deadline.c
> +++ b/kernel/sched/deadline.c
> @@ -733,6 +733,7 @@ static inline void replenish_dl_new_period(struct sched_dl_entity *dl_se,
>  		dl_se->dl_throttled = 1;
>  		dl_se->dl_defer_armed = 1;
>  	}
> +	trace_sched_dl_replenish_tp(dl_se, cpu_of(rq));
>  }
>  
>  /*
> @@ -850,6 +851,8 @@ static void replenish_dl_entity(struct sched_dl_entity *dl_se)
>  	if (dl_se->dl_throttled)
>  		dl_se->dl_throttled = 0;
>  
> +	trace_sched_dl_replenish_tp(dl_se, cpu_of(rq));
> +
>  	/*
>  	 * If this is the replenishment of a deferred reservation,
>  	 * clear the flag and return.
> @@ -1341,6 +1344,7 @@ static inline void dl_check_constrained_dl(struct sched_dl_entity *dl_se)
>  	    dl_time_before(rq_clock(rq), dl_next_period(dl_se))) {
>  		if (unlikely(is_dl_boosted(dl_se) || !start_dl_timer(dl_se)))
>  			return;
> +		trace_sched_dl_throttle_tp(dl_se, cpu_of(rq));
>  		dl_se->dl_throttled = 1;
>  		if (dl_se->runtime > 0)
>  			dl_se->runtime = 0;
> @@ -1504,6 +1508,7 @@ static void update_curr_dl_se(struct rq *rq, struct sched_dl_entity *dl_se, s64
>  
>  throttle:
>  	if (dl_runtime_exceeded(dl_se) || dl_se->dl_yielded) {
> +		trace_sched_dl_throttle_tp(dl_se, cpu_of(rq));
>  		dl_se->dl_throttled = 1;
>  
>  		/* If requested, inform the user about runtime overruns. */
> @@ -1795,6 +1800,7 @@ void dl_server_start(struct sched_dl_entity *dl_se)
>  	if (WARN_ON_ONCE(!cpu_online(cpu_of(rq))))
>  		return;
>  
> +	trace_sched_dl_server_start_tp(dl_se, cpu_of(rq));
>  	dl_se->dl_server_active = 1;
>  	enqueue_dl_entity(dl_se, ENQUEUE_WAKEUP);
>  	if (!dl_task(dl_se->rq->curr) || dl_entity_preempt(dl_se, &rq->curr->dl))
> @@ -1806,6 +1812,7 @@ void dl_server_stop(struct sched_dl_entity *dl_se)
>  	if (!dl_server(dl_se) || !dl_server_active(dl_se))
>  		return;
>  
> +	trace_sched_dl_server_stop_tp(dl_se, cpu_of(dl_se->rq));
>  	dequeue_dl_entity(dl_se, DEQUEUE_SLEEP);
>  	hrtimer_try_to_cancel(&dl_se->dl_timer);
>  	dl_se->dl_defer_armed = 0;
> -- 
> 2.52.0
> 
> 

--