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Subject: Re: [RFC][PATCH] perf_events, x86: PEBS support
From: Peter Zijlstra <peterz@infradead.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>, Stephane Eranian <eranian@google.com>,
       "Metzger, Markus T" <markus.t.metzger@intel.com>,
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       "H. Peter Anvin" <hpa@zytor.com>
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Date: Tue, 02 Feb 2010 19:33:08 +0100
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On Tue, 2010-02-02 at 19:26 +0100, Ingo Molnar wrote:
> * Peter Zijlstra <peterz@infradead.org> wrote:

> > @@ -203,8 +203,9 @@ struct perf_event_attr {
> >  				enable_on_exec :  1, /* next exec enables     */
> >  				task           :  1, /* trace fork/exit       */
> >  				watermark      :  1, /* wakeup_watermark      */
> > +				precise        :  1,
> 
> I think we want to default to precise events even if not specifically 
> requested by user-space, in the cases where that's possible on the CPU 
> without additional limitations.
> 
> That way people will default to better (and possibly cheaper) PEBS profiling 
> on modern Intel CPUs.

Sure, I'll look at that once it starts working :-)