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

[Phil Auld]

Hi Peter,

On Tue, Aug 15, 2023 at 01:01:24PM +0200 Peter Zijlstra wrote:
> From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> 
> There are currently two implementations of this basic __schedule()
> loop, and there is soon to be a third.
> 
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> Link: https://lkml.kernel.org/r/20230427111937.2745231-2-bigeasy@xxxxxxxxxxxxx
> ---
>  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
> 
> 

--