linux-kernel - Re: [PATCH] perf report: Fix branch stack mode cannot be set

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Message-ID: <54F03FD4.9030200@huawei.com>
Date:	Fri, 27 Feb 2015 17:58:44 +0800
From:	He Kuang <hekuang@...wei.com>
To:	<a.p.zijlstra@...llo.nl>, <paulus@...ba.org>, <mingo@...hat.com>,
	<acme@...nel.org>
CC:	<wangnan0@...wei.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] perf report: Fix branch stack mode cannot be set

ping..
在 2015/2/15 10:33, He Kuang 写道:
> When perf.data file be abtained by using 'perf record -b', perf report
> should use branch stack mode to generate output. But this function is
> broken by improper comparison between boolean and constant -1.
>
> before this patch:
> $perf report -b -i perf.data
> Samples: 16  of event 'cycles', Event count (approx.): 3171896
> Overhead  Command  Shared Object      Symbol
>    13.59%  ls       [kernel.kallsyms]  [k] prio_tree_remove
>    13.16%  ls       [kernel.kallsyms]  [k] change_pte_range
>    12.09%  ls       [kernel.kallsyms]  [k] page_fault
>    12.02%  ls       [kernel.kallsyms]  [k] zap_pte_range
> ...
>
> after this patch:
> $perf report -b -i perf.data
> Samples: 256  of event 'cycles', Event count (approx.): 256
> Overhead  Command  Source Shared Object  Source Symbol                               Target Shared Object  Target Symbol
>     9.38%  ls       [unknown]             [k] 0000000000000000                        [unknown]             [k] 0000000000000000
>     6.25%  ls       libc-2.19.so          [.] _dl_addr                                libc-2.19.so          [.] _dl_addr
>     6.25%  ls       [kernel.kallsyms]     [k] zap_pte_range                           [kernel.kallsyms]     [k] zap_pte_range
>     6.25%  ls       [kernel.kallsyms]     [k] change_pte_range                        [kernel.kallsyms]     [k] change_pte_range
>     0.39%  ls       [kernel.kallsyms]     [k] prio_tree_remove                        [kernel.kallsyms]     [k] prio_tree_remove
> ...
>
> Signed-off-by: He Kuang <hekuang@...wei.com>
> ---
>   tools/perf/builtin-report.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
> index 2f91094..ecc453b 100644
> --- a/tools/perf/builtin-report.c
> +++ b/tools/perf/builtin-report.c
> @@ -766,7 +766,7 @@ repeat:
>   	 * 0/1 means the user chose a mode.
>   	 */
>   	if (((branch_mode == -1 && has_br_stack) || branch_mode == 1) &&
> -	    branch_call_mode == -1) {
> +	    !branch_call_mode) {
>   		sort__mode = SORT_MODE__BRANCH;
>   		symbol_conf.cumulate_callchain = false;
>   	}


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