Subject: Re: [PATCH 1/4 tip/sched/core] sched: rename preempt_notifier to sched_notifier and always enable it

From: Paul Mackerras <[email-masked]>
Date: Fri, 27 Nov 2009 14:33:22 +1100

Ingo Molnar writes:

> The sched notifiers and the various event notifiers we have in the same 
> codepaths should really be unified into a single callback framework.
> 
> We have these _5_ callbacks:
> 
> ...
>         perf_event_task_sched_out(prev, next, cpu);
> ...
>         fire_sched_out_notifiers(prev, next);
> ...
>         trace_sched_switch(rq, prev, next);
> ...
>         perf_event_task_sched_in(current, cpu_of(rq));
> 	fire_sched_in_notifiers(current);
> ...
> 
> That could be done with just two callbacks - one for sched-out, one for 
> sched-in.
> 
> The best way to do that would be to use two TRACE_EVENT() callbacks, 
> make them unconditional and register to them. (with wrappers to make it 
> all convenient to use)

I'd rather 5 explicit direct function calls than two direct calls and
five indirect function calls, actually...

Paul.