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

[Peter Zijlstra <peterz@infradead.org>]

On Tue, 2010-05-11 at 17:37 +0200, Borislav Petkov wrote:
> From: Peter Zijlstra <peterz@infradead.org>
> Date: Tue, May 11, 2010 at 10:25:15AM -0400
> 
> > On Tue, 2010-05-11 at 16:15 +0200, Borislav Petkov wrote:
> > > Another point I have is that MCEs don't need pmus so we should consider
> > > having the ability to decouple events from pmus.
> > 
> > Strictly speaking tracepoints are software events, which run off of a
> > software 'pmu'. So no, we can't decouple, they need a 'pmu' context.
> 
> We could make this configurable depending on the severity of the error.
> I'm guessing for further event handling through the perf infrastructure
> we cannot run without a sw pmu context but on critical conditions
> we need to run as fast and as sparingly as possible so I'm thinking
> maybe adding some specially tailored callbacks to the MCE tracepoint
> trace_mce_record, as Steven suggested.

Well, all the tracepoint stuff should already be NMI-safe (all of perf
events needs to be because the PMI is an NMI) and I think perf as a
whole would like to run as fast as possible, so I don't yet see the need
for special purpose hooks (which I'll try to resist as much as
possible).