Re: [RFC][PATCH] perf: Rewrite core context handling

From: Peter Zijlstra
Date: Wed Oct 17 2018 - 13:20:16 EST

On Wed, Oct 17, 2018 at 04:43:27PM +0000, Song Liu wrote:

> > That makes task and cpu contexts wildly different, which will complicate
> > matters I feel.
> >
> I think we only need different logic when adding events to the task/cpu
> contexts. The ctx_sched_in() and ctx_sched_out() will need some extra
> logic to filter out events that are not being scheduled (don't schedule
> events on PMU-a when rotating PMU-b). This logic will be the same for
> task and cpu context. The difference is, the CPU context will not have
> such events, because we never added such event to CPU context.
> Does this make sense? I could try draft a RFC to see how difficult it is.

I'm not sure it saves much, if we have multiple per-cpu contexts we get
to re-introduce the active_ctx_list and loose the simplification for the
online status.

Plus that fundamental assymetry -- which would bother my OCD forever
more :-)