linux-kernel - Re: [PATCH] kernel/time/posix-cpu-timers: Remove useless call to check_dl

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Message-ID: <20181107095627.13e9c187@gandalf.local.home>
Date:   Wed, 7 Nov 2018 09:56:27 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Juri Lelli <juri.lelli@...hat.com>
Cc:     peterz@...radead.org, mingo@...hat.com, tglx@...utronix.de,
        linux-kernel@...r.kernel.org, luca.abeni@...tannapisa.it,
        claudio@...dence.eu.com, bristot@...hat.com,
        linux-rt-users@...r.kernel.org, mtk.manpages@...il.com,
        Mathieu Poirier <mathieu.poirier@...aro.org>
Subject: Re: [PATCH] kernel/time/posix-cpu-timers: Remove useless call to
 check_dl_overrun

On Wed,  7 Nov 2018 12:10:32 +0100
Juri Lelli <juri.lelli@...hat.com> wrote:

> check_dl_overrun is used to send a SIGXCPU to users that asked to be
> informed when SCHED_DEADLINE runtime overruns occur.
> 
> The function is called by check_thread_timers already, so the call in
> check_process_timers is redundant/wrong (even though harmless).
> 
> Remove it.
> 
> Fixes: 34be39305a77 ("sched/deadline: Implement "runtime overrun signal" support")
> Signed-off-by: Juri Lelli <juri.lelli@...hat.com>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Luca Abeni <luca.abeni@...tannapisa.it>
> Cc: Claudio Scordino <claudio@...dence.eu.com>
> Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
> ---
>  kernel/time/posix-cpu-timers.c | 3 ---
>  1 file changed, 3 deletions(-)
> 
> diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
> index ce32cf741b25..8f0644af40be 100644
> --- a/kernel/time/posix-cpu-timers.c
> +++ b/kernel/time/posix-cpu-timers.c
> @@ -917,9 +917,6 @@ static void check_process_timers(struct task_struct *tsk,
>  	struct task_cputime cputime;
>  	unsigned long soft;
>  
> -	if (dl_task(tsk))
> -		check_dl_overrun(tsk);
> -

Hmm, I wonder if we should just move this check directly into
run_posix_cpu_timers() directly. Why is it hidden in this call?

-- Steve


>  	/*
>  	 * If cputimer is not running, then there are no active
>  	 * process wide timers (POSIX 1.b, itimers, RLIMIT_CPU).