Re: [PATCH 3/6] sched: Extract __schedule_loop()

Phil Auld
2023-08-15T22:35:09Z

Hi Peter,

On Tue, Aug 15, 2023 at 01:01:24PM +0200 Peter Zijlstra wrote:
> From: Thomas Gleixner <tglx@linutronix.de>
>
> There are currently two implementations of this basic __schedule()
> loop, and there is soon to be a third.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> Link: https://lkml.kernel.org/r/20230427111937.2745231-2-bigeasy@linutronix.de
> ---
> kernel/sched/core.c | 21 +++++++++++----------
> 1 file changed, 11 insertions(+), 10 deletions(-)
>
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -6787,16 +6787,21 @@ static void sched_update_worker(struct t
> }
> }
>
> -asmlinkage __visible void __sched schedule(void)
> +static __always_inline void __schedule_loop(unsigned int sched_mode)

I think this needs __sched or it's the only thing that ever shows up
in wchan. E.g.

16995 0 bash S __schedule_loop.constprop.0
17036 1 kworker/ I __schedule_loop.constprop.0
17151 1 kworker/ I __schedule_loop.constprop.0
17235 0 sleep S __schedule_loop.constprop.0
17236 4 ps R -

vs

10417 1 kworker/ I worker_thread
10665 1 kworker/ I worker_thread
10670 4 sshd D -
10674 4 bash S do_wait
10701 0 sleep S hrtimer_nanosleep
10702 4 ps R -

Otherwise, looking forward to getting this and the rest of RT in...

Cheers,
Phil

> {
> - struct task_struct *tsk = current;
> -
> - sched_submit_work(tsk);
> do {
> preempt_disable();
> - __schedule(SM_NONE);
> + __schedule(sched_mode);
> sched_preempt_enable_no_resched();
> } while (need_resched());
> +}
> +
> +asmlinkage __visible void __sched schedule(void)
> +{
> + struct task_struct *tsk = current;
> +
> + sched_submit_work(tsk);
> + __schedule_loop(SM_NONE);
> sched_update_worker(tsk);
> }
> EXPORT_SYMBOL(schedule);
> @@ -6860,11 +6865,7 @@ void __sched schedule_preempt_disabled(v
> #ifdef CONFIG_PREEMPT_RT
> void __sched notrace schedule_rtlock(void)
> {
> - do {
> - preempt_disable();
> - __schedule(SM_RTLOCK_WAIT);
> - sched_preempt_enable_no_resched();
> - } while (need_resched());
> + __schedule_loop(SM_RTLOCK_WAIT);
> }
> NOKPROBE_SYMBOL(schedule_rtlock);
> #endif
>
>

--