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Date: Wed, 3 Mar 2010 21:07:31 +0100
From: Frederic Weisbecker <fweisbec@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>, LKML <linux-kernel@vger.kernel.org>,
       Thomas Gleixner <tglx@linutronix.de>, "H. Peter Anvin" <hpa@zytor.com>,
       Paul Mackerras <paulus@samba.org>, Steven Rostedt <rostedt@goodmis.org>,
       Arnaldo Carvalho de Melo <acme@redhat.com>
Subject: Re: [RFC][PATCH 2/3] perf: Take a hot regs snapshot for trace
	events
Message-ID: <20100303200727.GA5194@nowhere>
References: <1267599302-2886-1-git-send-regression-fweisbec@gmail.com> <1267599302-2886-3-git-send-regression-fweisbec@gmail.com> <1267605529.25158.75.camel@laptop>
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On Wed, Mar 03, 2010 at 09:38:49AM +0100, Peter Zijlstra wrote:
> On Wed, 2010-03-03 at 07:55 +0100, Frederic Weisbecker wrote:
> >  /*
> > + * Hot regs snapshot support -- arch specific
> > + * This needs to be a macro because we want the current
> > + * frame pointer.
> > + */
> > +#ifndef PERF_SAVE_REGS
> > +#define PERF_SAVE_REGS(regs)   memset(regs, 0, sizeof(*regs));
> > +#endif
> 
> It would be nice to have the fallback at least set the current or
> calling IP, now you've basically wrecked stuff for everything !x86.


Oh I haven't wrecked that much !x86, no callchain was working on
trace events before, nor the ip was correct :-)

That said I agree with you, I'm going to reuse the CALLER_ADDRx
macros for that. This is the occasion to add a skip field
in PERF_SAVE_REGS to rewind where we want.

Thanks.