linux-kernel - Re: [PATCH v2 -tip] perf probe: Add fastpath to do lookup by function name

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Date:	Fri, 25 Mar 2011 14:33:45 +0800
From:	Lin Ming <ming.m.lin@...el.com>
To:	Arnaldo Carvalho de Melo <acme@...radead.org>
Cc:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Ingo Molnar <mingo@...e.hu>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 -tip] perf probe: Add fastpath to do lookup by
 function name

在 2011-03-25五的 10:57 +0800，Arnaldo Carvalho de Melo写道：
> Em Fri, Mar 25, 2011 at 10:14:25AM +0900, Masami Hiramatsu escreveu:
> > (2011/03/24 23:09), Lin Ming wrote:
> > > v2 -> v1:
> > > - Don't compare file names with cu_find_realpath(...), instead, compare them
> > >   with the name returned by dwarf_decl_file(sp_die) 
> > > 
> > > The vmlinux file may have thousands of CUs.
> > > We can lookup function name from .debug_pubnames section
> > > to avoid the slow loop on CUs.
> > > 
> > > ./perf stat -r 10 -- ./perf probe -k /home/mlin/vmlinux \
> > >         -s /home/mlin/linux-2.6 \
> > > 	--line csum_partial_copy_to_user > tmp.log
> > > 
> > > before patch applied
> > > =====================
> > >         364.535892 task-clock-msecs         #      0.997 CPUs
> > >                  0 context-switches         #      0.000 M/sec
> > >                  0 CPU-migrations           #      0.000 M/sec
> > >             29,993 page-faults              #      0.082 M/sec
> > >        865,862,109 cycles                   #   2375.245 M/sec
> > >      1,255,259,630 instructions             #      1.450 IPC
> > >        252,400,884 branches                 #    692.390 M/sec
> > >          3,429,376 branch-misses            #      1.359 %
> > >          1,386,990 cache-references         #      3.805 M/sec
> > >            687,188 cache-misses             #      1.885 M/sec
> > > 
> > >         0.365792170  seconds time elapsed
> > > 
> > > after patch applied
> > > =====================
> > >          89.896405 task-clock-msecs         #      0.991 CPUs
> > >                  1 context-switches         #      0.000 M/sec
> > >                  0 CPU-migrations           #      0.000 M/sec
> > >             10,145 page-faults              #      0.113 M/sec
> > >        214,553,875 cycles                   #   2386.679 M/sec
> > >        226,915,559 instructions             #      1.058 IPC
> > >         44,536,614 branches                 #    495.422 M/sec
> > >            613,074 branch-misses            #      1.377 %
> > >            860,787 cache-references         #      9.575 M/sec
> > >            442,380 cache-misses             #      4.921 M/sec
> > > 
> > >         0.090716032  seconds time elapsed
> > 
> > Thanks! Looks very good :)
> > 
> > Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
> 
> Indeed, I'll try and process this one tomorrow,

Except find_line_range, I just realized that the same optimization maybe
added for find_probes.

Thanks,
Lin Ming

> 
> Thanks a lot!
> 
> - Arnaldo


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