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From:   Vincent Guittot <vincent.guittot@linaro.org>
Date:   Wed, 22 Apr 2020 15:21:45 +0200
Message-ID: <CAKfTPtB8NiKqggZN3v6u=Rdwj4grzRwn1mW31ov0y5ZhDBcvuw@mail.gmail.com>
Subject: Re: [PATCH 13/23] sched,ion: Convert to sched_set_normal()
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Ingo Molnar <mingo@kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Steven Rostedt <rostedt@goodmis.org>,
        Qais Yousef <qais.yousef@arm.com>,
        Juri Lelli <juri.lelli@redhat.com>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
        John Stultz <john.stultz@linaro.org>
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On Wed, 22 Apr 2020 at 13:29, Peter Zijlstra <peterz@infradead.org> wrote:
>
> In an attempt to take away sched_setscheduler() from modules, change
> this into sched_set_normal(.nice = 19).
>
> Cc: john.stultz@linaro.org
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> Reviewed-by: Ingo Molnar <mingo@kernel.org>
> ---
>  drivers/staging/android/ion/ion_heap.c |    3 ---
>  1 file changed, 3 deletions(-)
>
> --- a/drivers/staging/android/ion/ion_heap.c
> +++ b/drivers/staging/android/ion/ion_heap.c
> @@ -244,8 +244,6 @@ static int ion_heap_deferred_free(void *
>
>  int ion_heap_init_deferred_free(struct ion_heap *heap)
>  {
> -       struct sched_param param = { .sched_priority = 0 };
> -
>         INIT_LIST_HEAD(&heap->free_list);
>         init_waitqueue_head(&heap->waitqueue);
>         heap->task = kthread_run(ion_heap_deferred_free, heap,
> @@ -255,7 +253,7 @@ int ion_heap_init_deferred_free(struct i
>                        __func__);
>                 return PTR_ERR_OR_ZERO(heap->task);
>         }
> -       sched_setscheduler(heap->task, SCHED_IDLE, &param);
> +       sched_set_normal(heap->task, 19);

Would it make sense to have a sched_set_idle(task) to enable kernel
setting SCHED_IDLE task ?

SCHED_NORMAL w/ nice 19 and SCHED_IDLE tasks are not treated in the
same way when checking for preemption at  wakeup

>
>         return 0;
>  }
>
>