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From: Paul Mackerras <paulus@samba.org>
To: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: perf_counters: page fault trace record
Date: Sat, 13 Jun 2009 19:17:57 +1000	[thread overview]
Message-ID: <18995.28357.164575.925080@cargo.ozlabs.ibm.com> (raw)
In-Reply-To: <4A336700.3060309@linux.vnet.ibm.com>

Corey Ashford writes:

> Paul Mackerras wrote:
> > Can't you do what you need just using a page fault software counter
> > with sample_type = PERF_SAMPLE_IP | PERF_SAMPLE_ADDR and
> > sample_period = 1?
> 
> I thought about that, but I was under the (incorrect?) impression that 
> on Power, the PERF_SAMPLE_ADDR would be set by the value of the SDAR 
> register, which wouldn't be correct for the case of a page fault.

No, the PERF_SAMPLE_ADDR value only comes from SDAR for a hardware
counter overflow event.  For the page-fault software counter the
PERF_SAMPLE_ADDR value will always be the faulting address.

Paul.

  reply	other threads:[~2009-06-13  9:18 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-06-13  1:25 Corey Ashford
2009-06-13  3:43 ` Paul Mackerras
2009-06-13  7:04   ` Ingo Molnar
2009-06-13  8:44   ` Corey Ashford
2009-06-13  9:17     ` Paul Mackerras [this message]
2009-06-13 10:09       ` Ingo Molnar
2009-06-15 20:38         ` Corey Ashford

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