Date: Fri, 6 Mar 2009 18:10:16 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Larry Woodman <lwoodman@redhat.com>,
       Andrew Morton <akpm@linux-foundation.org>,
       Nick Piggin <npiggin@suse.de>
Cc: Steven Rostedt <rostedt@goodmis.org>,
       KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
       linux-kernel@vger.kernel.org, peterz@infradead.org, fweisbec@gmail.com,
       Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [Patch] mm tracepoints
Message-ID: <20090306171016.GA32128@elte.hu>
References: <1233306324.11332.11.camel@nigel-laptop> <1236291400.1476.50.camel@dhcp-100-19-198.bos.redhat.com> <20090306105627.3EF0.A69D9226@jp.fujitsu.com> <alpine.DEB.2.00.0903052124240.14535@gandalf.stny.rr.com> <20090306110423.GD21168@elte.hu> <1236342797.3154.1.camel@dhcp47-138.lab.bos.redhat.com> <20090306135547.GB21907@elte.hu> <1236358657.1476.56.camel@dhcp-100-19-198.bos.redhat.com>
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* Larry Woodman <lwoodman@redhat.com> wrote:

> > Would that be useless or controversial? We know from 
> > vma->mapping which inode it maps to. Knowing which file is 
> > faulting in can be useful - especially when addresses are a 
> > moving target such as under PIE or with dlopen(), etc.
> > 
> > 	Ingo
> 
> Attached is the updated patch that applies and builds 
> correctly (sorry I missed the lockdep tracepoints that were 
> added at the last minute). [...]

Looks pretty good and useful to me. I've Cc:-ed more mm folks, 
it would be nice to hear their opinion about these tracepoints.

Andrew, Nick, Peter, what do you think?

About the motivation of these tracepoints: i suspect these 
tracepoints reflect your years-long experience in dealing with 
various MM regressions in the enterprise space and these 
tracepoints would help understand such regressions 
faster/easier?

> [...]  As far as the filename:offset is concerned I am working 
> on that.  Its not as simple as it looks because we have to 
> follow a variable list of structs that can be null terminated 
> several places along the way.

It's definitely not simple! I dont think it should be in this 
base patch at all - it should be an add-on.

	Ingo
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