Re: [PATCH 2/2 tip] perf: report should only load text symbols from kallsyms

[Ingo Molnar <mingo@elte.hu>]

* Arnaldo Carvalho de Melo <acme@redhat.com> wrote:

> >From 7508bc84d541ac245be633803d393244b6860af6 Mon Sep 17 00:00:00 2001
> From: Arnaldo Carvalho de Melo <acme@redhat.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@emilia ~]$ 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@emilia ~]$ 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@emilia ~]$
> 
> After:
> 
> acme@emilia ~]$ 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@emilia ~]$ 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@emilia ~]$
> 
> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.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