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

From: Peter Zijlstra
Date: Tue May 11 2010 - 05:25:27 EST


On Tue, 2010-05-11 at 11:18 +0200, Ingo Molnar wrote:
> * Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>
> > The new PMUs will use a dynamic range that starts at PERF_TYPE_MAX.
>
> I dont think we should use a dynamic range of event sources - it's a
> completely useless indirection that has no meaning to humans.
>
> As far as machine interfaces go a much cleaner approach would be to allow an
> open fd to a sysfs file to be passed to sys_perf_event_open() - this would
> identify the event source. This needs a small extension of the ABI but we
> could thus get rid of the 'type' enumeration altogether and express _all_
> event sources via fds to sysfs files.

Whatever, that's almost identical. What we can do is reserve
perf_event_attr::type with bit 31 set for fd's and use the fd->file
lookup instead of the type->pmu lookup.
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