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Subject: Re: [RFC][PATCH 2/3] perf: Take a hot regs snapshot for trace
 events
From: Steven Rostedt <rostedt@goodmis.org>
Reply-To: rostedt@goodmis.org
To: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>, Ingo Molnar <mingo@elte.hu>,
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       Arnaldo Carvalho de Melo <acme@redhat.com>
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On Wed, 2010-03-03 at 17:37 +0100, Peter Zijlstra wrote:

> > >  	/* Trace events already protected against recursion */
> > >  	do_perf_sw_event(PERF_TYPE_TRACEPOINT, event_id, count, 1,
> > > -				&data, regs);
> > > +				&data, &regs);
> > 
> > Off-topic: Why is the above a perf sw event? Couldn't that also be a
> > normal TRACE_EVENT()?
> 
> Well, no, this is the stuff that transforms TRACE_EVENT() into perf
> software events ;-)
> 

oops, my bad :-), I thought this was in the x86 arch directory. For the
University, I was helping them with adding trace points for page faults
when I came across this in arch/x86/mm/fault.c:

	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, 0, regs, address);


This is what I actually was wondering about. Why is it a "perf only"
trace point instead of a TRACE_EVENT()?

-- Steve