Message-ID: <4A336700.3060309@linux.vnet.ibm.com>
Date: Sat, 13 Jun 2009 01:44:48 -0700
From: Corey Ashford <cjashfor@linux.vnet.ibm.com>
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To: Paul Mackerras <paulus@samba.org>
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
References: <4A330022.3070105@linux.vnet.ibm.com> <18995.8319.322002.917595@cargo.ozlabs.ibm.com>
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Paul Mackerras wrote:
> Corey Ashford writes:
> 
>> One of the tools we are working on needs to be able to look not only at counts 
>> of page faults, but where they are occurring (ip and faulting page address).
>>
>> What would you think about adding a new bit to the config record, something like:
> 
> 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.

I need to go look at the kernel code :)

- Corey

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