Date: Sat, 13 Jun 2009 09:04:11 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>,
       LKML <linux-kernel@vger.kernel.org>,
       Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: perf_counters: page fault trace record
Message-ID: <20090613070411.GA6682@elte.hu>
References: <4A330022.3070105@linux.vnet.ibm.com> <18995.8319.322002.917595@cargo.ozlabs.ibm.com>
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* Paul Mackerras <paulus@samba.org> 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?

Yes, we should use a generic 'data address' field. A whole lot of 
interesting events can live with that - only full-blown generic 
tracepoints have more complex sample record formats.

Also, if this feature is added to pagefaults, please also add 
support for it into tools/perf/, so that it gets tested/used.

Thanks,

	Ingo
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