linux-kernel - Re: [PATCH 0/3] perf tools: Speedup DWARF unwind

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Message-ID: <20140418093506.GA1914@krava.brq.redhat.com>
Date:	Fri, 18 Apr 2014 11:35:07 +0200
From:	Jiri Olsa <jolsa@...hat.com>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	linux-kernel@...r.kernel.org,
	Corey Ashford <cjashfor@...ux.vnet.ibm.com>,
	David Ahern <dsahern@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Paul Mackerras <paulus@...ba.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Jean Pihet <jean.pihet@...aro.org>
Subject: Re: [PATCH 0/3] perf tools: Speedup DWARF unwind

On Fri, Apr 18, 2014 at 09:55:25AM +0200, Ingo Molnar wrote:
> 
> * Ingo Molnar <mingo@...nel.org> wrote:
> 
> > 
> > * Jiri Olsa <jolsa@...hat.com> wrote:
> > 
> > > hi,
> > > trying to speedup DWARF unwind report code by factoring
> > > related code:
> > >   - caching sample's registers access
> > >   - keep dso data file descriptor open for the
> > >     life of the dso object
> > >   - replace dso cache code by mapping dso data file
> > >     directly for the life of the dso object
> > > 
> > > The speedup is mainly for libunwind unwind. The libdw will benefit
> > > mainly from cached registers access, because it handles dso data
> > > accesses by itself.. and anyway it's still faster ;-).
> > 
> > Just curious: do you have any numbers about how much faster it got in 
> > practice?
> 
> Oh, the numbers are all in the changelogs, never mind!
> 
> So in your test workload it went from 54.6 seconds to 36.7, a 48% 
> speedup :-)
> 

yep, I should have put it in here as well.. also the current
libdw unwind time on this workload is 26 seconds.. 10 more
seconds to go ;-)

jirka
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