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Date: Wed, 27 May 2009 08:10:01 +0200
From: Ingo Molnar <mingo@...e.hu>
To: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Paul Mackerras <paulus@...ba.org>,
Mike Galbraith <efault@....de>,
Thomas Gleixner <tglx@...utronix.de>,
Steven Rostedt <rostedt@...dmis.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2 tip] perf: report should only load text symbols
from kallsyms
* Arnaldo Carvalho de Melo <acme@...hat.com> wrote:
> >From 7508bc84d541ac245be633803d393244b6860af6 Mon Sep 17 00:00:00 2001
> From: Arnaldo Carvalho de Melo <acme@...hat.com>
> Date: Tue, 26 May 2009 19:14:47 -0300
> Subject: [PATCH] perf: report should only load text symbols from kallsyms
>
> Just like we do for userspace when reading the symtab, reducing the
> number of entries we insert on the symbols rbtree.
>
> Before:
>
> [acme@...lia ~]$ rm -f perf_report.perf ; perf record -o perf_report.perf perf stat perf report > /dev/null
>
> Performance counter stats for 'perf':
>
> 218.138382 task clock ticks (msecs)
> 4 context switches (events)
> 8 CPU migrations (events)
> 2136 pagefaults (events)
> 32746212 CPU cycles (events) (scaled from 67.04%)
> 11961102 instructions (events) (scaled from 66.19%)
> 49841 cache references (events) (scaled from 21.96%)
> 13777 cache misses (events) (scaled from 21.98%)
>
> Wall-clock time elapsed: 218.702477 msecs
>
> [acme@...lia ~]$ perf report -i perf_report.perf | head
> 11.06 perf [.] 0x00000000000057cb /home/acme/git/linux-2.6-tip/Documentation/perf_counter/perf: dso__find_symbol
> 9.15 perf [.] 0x00000000000056a0 /home/acme/git/linux-2.6-tip/Documentation/perf_counter/perf: dso__insert_symbol
> 8.72 perf [k] 0xffffffff8101b1d2 intel_pmu_enable_all
> 8.51 perf [.] 0x0000000000006672 /home/acme/git/linux-2.6-tip/Documentation/perf_counter/perf: thread__symbol_incnew
> 3.83 perf [k] 0xffffffff811cfc5a vsnprintf
> 3.40 perf [.] 0x0000000000005e33 /home/acme/git/linux-2.6-tip/Documentation/perf_counter/perf: hex
> 3.40 perf [.] 0x0000000000005ec7 /home/acme/git/linux-2.6-tip/Documentation/perf_counter/perf: hex2long
> 3.19 perf [k] 0xffffffff811ce1c1 number
> 2.77 perf [.] 0x0000000000006869 /home/acme/git/linux-2.6-tip/Documentation/perf_counter/perf: threads__findnew
> 2.77 perf [.] 0x000000000000fde3 /home/acme/git/linux-2.6-tip/Documentation/perf_counter/perf: rb_insert_color
> [acme@...lia ~]$
>
> After:
>
> acme@...lia ~]$ rm -f perf_report.perf ; perf record -o perf_report.perf perf stat perf report > /dev/null
>
> Performance counter stats for 'perf':
>
> 190.228511 task clock ticks (msecs)
> 4 context switches (events)
> 7 CPU migrations (events)
> 1625 pagefaults (events)
> 29578745 CPU cycles (events) (scaled from 66.92%)
> 10516914 instructions (events) (scaled from 66.47%)
> 44015 cache references (events) (scaled from 22.04%)
> 8248 cache misses (events) (scaled from 22.07%)
>
> Wall-clock time elapsed: 190.816096 msecs
nice!
> [acme@...lia ~]$ perf report -i perf_report.perf | head
> 15.99 perf [.] 0x00000000000057a9 /home/acme/git/linux-2.6-tip/Documentation/perf_counter/perf: dso__find_symbol
> 10.87 perf [.] 0x000000000000674d /home/acme/git/linux-2.6-tip/Documentation/perf_counter/perf: thread__symbol_incnew
> 8.74 perf [k] 0xffffffff8101b1d2 intel_pmu_enable_all
> 5.54 perf [.] 0x0000000000005e42 /home/acme/git/linux-2.6-tip/Documentation/perf_counter/perf: hex
> 4.48 perf [.] 0x0000000000005ebe /home/acme/git/linux-2.6-tip/Documentation/perf_counter/perf: hex2long
> 4.48 perf [k] 0xffffffff811cfba0 vsnprintf
> 3.84 perf [.] 0x00000000000056b4 /home/acme/git/linux-2.6-tip/Documentation/perf_counter/perf: dso__insert_symbol
> 3.62 perf [.] 0x00000000000068d0 /home/acme/git/linux-2.6-tip/Documentation/perf_counter/perf: threads__findnew
> 3.20 perf [k] 0xffffffff811ce0b3 number
> 2.56 perf [.] 0x0000000000006d78 /home/acme/git/linux-2.6-tip/Documentation/perf_counter/perf: __cmd_report
> [acme@...lia ~]$
>
> Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
> ---
> Documentation/perf_counter/builtin-report.c | 14 +++++++++++---
> 1 files changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/perf_counter/builtin-report.c b/Documentation/perf_counter/builtin-report.c
> index c517483..a55f15d 100644
> --- a/Documentation/perf_counter/builtin-report.c
> +++ b/Documentation/perf_counter/builtin-report.c
> @@ -3,6 +3,7 @@
> #include <libelf.h>
> #include <gelf.h>
> #include <elf.h>
> +#include <ctype.h>
>
> #include "util/list.h"
> #include "util/rbtree.h"
> @@ -408,13 +409,20 @@ static int load_kallsyms(void)
>
> int len = hex2long(line, &start);
>
> - len += 3; /* ' t ' */
> - if (len >= line_len)
> + len++;
> + if (len + 2 >= line_len)
> + continue;
> +
> + char symbol_type = line[len];
> + /*
> + * We're interested only in code ('T'ext)
> + */
> + if (toupper(symbol_type) != 'T')
> continue;
We would also include ' W ' symbols, right?
Ingo
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