Re: [RFC][PATCH 09/11] perf_counter: revamp syscall input ABI

[Peter Zijlstra <a.p.zijlstra@chello.nl>]

On Wed, 2009-03-18 at 13:29 +1100, Paul Mackerras wrote:
> Peter Zijlstra writes:
> 
> > The hardware/software classification in hw_event->type became a little strained
> > due to the addition of tracepoint tracing.
> > 
> > Instead split up the field and provide a type field to explicitly specify the
> > counter type, while using the event_id field to specify which event to use.
> > 
> > Raw counters still work as before, only the raw config now goes into raw_event.
> 
> Interesting idea, but why not also use it to express the distinction
> between generic and raw hardware events ids?  Why not add a
> PERF_TYPE_RAW_HARDWARE to this list:
> 
> > + * hw_event.type
> > + */
> > +enum perf_event_types {
> > +	PERF_TYPE_HARDWARE		= 0,
> > +	PERF_TYPE_SOFTWARE		= 1,
> > +	PERF_TYPE_TRACEPOINT		= 2,
> > +};
> 
> and get rid of the raw bit?  That way, hw_event.raw_event is unique
> for every different event, whereas the way you have it, you still need
> to include the raw bit to get a unique id.

Ah, I thought we should keep a pure 64 bit raw value. You never know
what hardware will do.