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Message-ID: <20230531182629.nztie5rwhjl53v3d@airbuntu>
Date: Wed, 31 May 2023 19:26:29 +0100
From: Qais Yousef <qyousef@...alina.io>
To: Lukasz Luba <lukasz.luba@....com>
Cc: linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
rafael@...nel.org, linux-pm@...r.kernel.org, rostedt@...dmis.org,
mhiramat@...nel.org, mingo@...hat.com, peterz@...radead.org,
juri.lelli@...hat.com, vincent.guittot@...aro.org,
dietmar.eggemann@....com, bsegall@...gle.com, mgorman@...e.de,
bristot@...hat.com, vschneid@...hat.com, delyank@...com,
qyousef@...gle.com
Subject: Re: [RESEND][PATCH v2 1/3] sched/tp: Add new tracepoint to track
uclamp set from user-space
On 05/22/23 15:57, Lukasz Luba wrote:
> The user-space can set uclamp value for a given task. It impacts task
> placement decisions made by the scheduler. This is very useful information
> and helps to understand the system behavior or track improvements in
> middleware and applications which start using uclamp mechanisms and report
> better performance in tests.
Do you mind adding a generic one instead please? And explain why we can't just
attach to the syscall via kprobes? I think you want to bypass the permission
checks, so maybe a generic tracepoint after that might be justifiable?
Then anyone can use it to track how userspace has changed any attributes for
a task, not just uclamp.
Thanks
--
Qais Yousef
>
> Signed-off-by: Lukasz Luba <lukasz.luba@....com>
> ---
> include/trace/events/sched.h | 4 ++++
> kernel/sched/core.c | 5 +++++
> 2 files changed, 9 insertions(+)
>
> diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
> index fbb99a61f714..dbfb30809f15 100644
> --- a/include/trace/events/sched.h
> +++ b/include/trace/events/sched.h
> @@ -735,6 +735,10 @@ DECLARE_TRACE(sched_update_nr_running_tp,
> TP_PROTO(struct rq *rq, int change),
> TP_ARGS(rq, change));
>
> +DECLARE_TRACE(uclamp_update_tsk_tp,
> + TP_PROTO(struct task_struct *tsk, int uclamp_id, unsigned int value),
> + TP_ARGS(tsk, uclamp_id, value));
> +
> #endif /* _TRACE_SCHED_H */
>
> /* This part must be outside protection */
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 944c3ae39861..7b9b800ebb6c 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -114,6 +114,7 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(sched_overutilized_tp);
> EXPORT_TRACEPOINT_SYMBOL_GPL(sched_util_est_cfs_tp);
> EXPORT_TRACEPOINT_SYMBOL_GPL(sched_util_est_se_tp);
> EXPORT_TRACEPOINT_SYMBOL_GPL(sched_update_nr_running_tp);
> +EXPORT_TRACEPOINT_SYMBOL_GPL(uclamp_update_tsk_tp);
>
> DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
>
> @@ -1956,12 +1957,16 @@ static void __setscheduler_uclamp(struct task_struct *p,
> attr->sched_util_min != -1) {
> uclamp_se_set(&p->uclamp_req[UCLAMP_MIN],
> attr->sched_util_min, true);
> + trace_uclamp_update_tsk_tp(p, UCLAMP_MIN,
> + attr->sched_util_min);
> }
>
> if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MAX &&
> attr->sched_util_max != -1) {
> uclamp_se_set(&p->uclamp_req[UCLAMP_MAX],
> attr->sched_util_max, true);
> + trace_uclamp_update_tsk_tp(p, UCLAMP_MAX,
> + attr->sched_util_max);
> }
> }
>
> --
> 2.25.1
>
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