linux-kernel - Re: [patch 0/4] perf_counter tools: support annotation of live kernel modules

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Message-ID: <20090703085338.GI21833@elte.hu>
Date:	Fri, 3 Jul 2009 10:53:38 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	Mike Galbraith <efault@....de>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Paul Mackerras <paulus@...ba.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [patch 0/4] perf_counter tools: support annotation of live
	kernel modules


* Frederic Weisbecker <fweisbec@...il.com> wrote:

> On Fri, Jul 03, 2009 at 09:17:39AM +0200, Mike Galbraith wrote:
> > On Thu, 2009-07-02 at 14:10 +0200, Peter Zijlstra wrote:
> > > On Thu, 2009-07-02 at 09:17 +0200, Mike Galbraith wrote:
> > > 
> > > >  I've been pondering a perf archive tool
> > > > that would package everything that's needed to do analysis on a
> > > > different box.  One big problem though, is that while you can easily
> > > > package vmlinux and modules, what about all the userland binaries?  A
> > > > large perf.data and/or debug info binaries can easily make transport
> > > > impractical enough.
> > > 
> > > I would simply extend the current file header with another section in
> > > which we do a structured storage of the data structures we currently
> > > build in perf-report. That is, the dso and symbol bits.
> > > 
> > > If we then run perf-report on a file containing such a section we read
> > > that data instead of trying to locate them the regular way.
> > 
> > That's a good idea.
> > 
> > If uname doesn't match stored record time uname, you're not live, so
> > tools require an exportable perf.data.  If you're not live and not on
> > the same host, annotate requires binaries appended via an export tool
> > with --sym-filter -k -u -% whatever capability.
> > 
> > 	-Mike
> 
> 
> Also that would make easier the implementation of a perf compare 
> thing. A perf compare may have several uses, including:
> 
> (1) comparing different workloads with a same executable.
> (2) comparing different executable versions for a same workload
> (3) (1) + (2) ?
> 
> For the (2), having self contained record files as operands would 
> let comparisons based on symbols, pretty useful when you have to 
> compare two different vmlinux (or whatever binary executable).

very good points.

	Ingo
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