Re: [RFC][PATCH 3/9] perf: export registerred pmus via sysfs

[Ingo Molnar <mingo@elte.hu>]

* Peter Zijlstra <peterz@infradead.org> wrote:

> On Mon, 2010-05-10 at 13:43 +0200, Ingo Molnar wrote:
> > 
> > Yeah, we really want a mechanism like this in place instead of continuing with 
> > the somewhat ad-hoc extensions to the event enumeration space.
> > 
> > One detail: i think we want one more level. Instead of:
> > 
> >  /sys/devices/system/node/nodeN/node_events
> >                                 node_events/event_source_id
> >                                 node_events/local_misses
> >                                            /local_hits
> >                                            /remote_misses
> >                                            /remote_hits
> >                                            /...
> > 
> > We want the individual events to be a directory, containing the event_id:
> > 
> >  /sys/devices/system/node/nodeN/node_events
> >                                 node_events/event_source_id
> >                                 node_events/local_misses/event_id
> >                                            /local_hits/event_id
> >                                            /remote_misses/event_id
> >                                            /remote_hits/event_id
> >                                            /...
> > 
> > The reason is that we want to keep our options open to add more attributes to 
> > individual events. (In fact extended attributes already exist for certain 
> > event classes - such as the 'format' info for tracepoints.) 
> 
> Sure, sounds like a sensible suggestion.
> 
> One thing I'd also like to clarify is that !raw events should not be 
> exhaustive hardware event lists, those are best left for userspace, but 
> instead are generally useful events that can be expected to be implemented 
> by any hardware of that particular class.
> 
> So a GPU might have things like 'vsync' and 'cmd_pipeline_stall' or whatever 
> is a generic GPU feature, but not very implementation specific things that 
> the next generation of hardware won't ever have.

Definitely so.

	Ingo