linux-kernel - Re: [PATCH] perf script: Fix display inconsitency when call-graph config is used

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Message-ID: <575141EC.5090806@huawei.com>
Date:	Fri, 3 Jun 2016 16:38:04 +0800
From:	"Wangnan (F)" <wangnan0@...wei.com>
To:	<acme@...nel.org>, <alexander.shishkin@...ux.intel.com>,
	<dsahern@...il.com>
CC:	He Kuang <hekuang@...wei.com>, <peterz@...radead.org>,
	<mingo@...hat.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] perf script: Fix display inconsitency when call-graph
 config is used

Hi, Arnaldo and David,

Could you please have a look at this patch? It solves a perf script 
problem when
dealing with mixed call-graph and no-call-graph events.

Thank you.

On 2016/5/16 12:51, He Kuang wrote:
> There's a display inconsistency when 'call-graph' config event appears
> in different position. The problem can be reproduced like this:
>
> We record signal_deliver with call-graph and signal_generate without it.
>
>    $ perf record -g -a -e signal:signal_deliver -e signal:signal_generate/call-graph=no/
>
>    [ perf record: Captured and wrote 0.017 MB perf.data (2 samples) ]
>
>    $ perf script
>
>    kworker/u2:1    13 [000]  6563.875949: signal:signal_generate: sig=2 errno=0 code=128 comm=perf pid=1313 grp=1 res=0 ff61cc __send_signal+0x3ec ([kernel.kallsyms])
>    perf  1313 [000]  6563.877584:  signal:signal_deliver: sig=2 errno=0 code=128 sa_handler=43115e sa_flags=14000000
>                7ffff314 get_signal+0x80007f0023a4 ([kernel.kallsyms])
>                7fffe358 do_signal+0x80007f002028 ([kernel.kallsyms])
>                7fffa5e8 exit_to_usermode_loop+0x80007f002053 ([kernel.kallsyms])
>                ...
>
> Then we exchange the order of these two events in commandline, and keep
> signal_generate without call-graph.
>
>    $ perf record -g -a -e signal:signal_generate/call-graph=no/ -e signal:signal_deliver
>
>    [ perf record: Captured and wrote 0.017 MB perf.data (2 samples) ]
>
>    $ perf script
>
>      kworker/u2:2  1314 [000]  6933.353060: signal:signal_generate: sig=2 errno=0 code=128 comm=perf pid=1321 grp=1 res=0
>              perf  1321 [000]  6933.353872:  signal:signal_deliver: sig=2 errno=0 code=128 sa_handler=43115e sa_flags=14000000
>
> This time, the callchain of the event signal_deliver disappeared. The
> problem is caused by that perf only checks for the first evsel in evlist
> and decides if callchain should be printed.
>
> This patch travseres all evsels in evlist to see if any of them have
> callchains, and shows the right result:
>
>    $ perf script
>
>    kworker/u2:2  1314 [000]  6933.353060: signal:signal_generate: sig=2 errno=0 code=128 comm=perf pid=1321 grp=1 res=0 ff61cc __send_signal+0x3ec ([kernel.kallsyms])
>    perf  1321 [000]  6933.353872:  signal:signal_deliver: sig=2 errno=0 code=128 sa_handler=43115e sa_flags=14000000
>                7ffff314 get_signal+0x80007f0023a4 ([kernel.kallsyms])
>                7fffe358 do_signal+0x80007f002028 ([kernel.kallsyms])
>                7fffa5e8 exit_to_usermode_loop+0x80007f002053 ([kernel.kallsyms])
>                ...
>
> Signed-off-by: He Kuang <hekuang@...wei.com>
> ---
>   tools/perf/builtin-script.c | 23 +++++++++++++----------
>   1 file changed, 13 insertions(+), 10 deletions(-)
>
> diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
> index efca816..7a18b92 100644
> --- a/tools/perf/builtin-script.c
> +++ b/tools/perf/builtin-script.c
> @@ -339,7 +339,7 @@ static void set_print_ip_opts(struct perf_event_attr *attr)
>    */
>   static int perf_session__check_output_opt(struct perf_session *session)
>   {
> -	int j;
> +	unsigned int j;
>   	struct perf_evsel *evsel;
>   
>   	for (j = 0; j < PERF_TYPE_MAX; ++j) {
> @@ -388,17 +388,20 @@ static int perf_session__check_output_opt(struct perf_session *session)
>   		struct perf_event_attr *attr;
>   
>   		j = PERF_TYPE_TRACEPOINT;
> -		evsel = perf_session__find_first_evtype(session, j);
> -		if (evsel == NULL)
> -			goto out;
>   
> -		attr = &evsel->attr;
> +		evlist__for_each(session->evlist, evsel) {
> +			if (evsel->attr.type != j)
> +				continue;
> +
> +			attr = &evsel->attr;
>   
> -		if (attr->sample_type & PERF_SAMPLE_CALLCHAIN) {
> -			output[j].fields |= PERF_OUTPUT_IP;
> -			output[j].fields |= PERF_OUTPUT_SYM;
> -			output[j].fields |= PERF_OUTPUT_DSO;
> -			set_print_ip_opts(attr);
> +			if (attr->sample_type & PERF_SAMPLE_CALLCHAIN) {
> +				output[j].fields |= PERF_OUTPUT_IP;
> +				output[j].fields |= PERF_OUTPUT_SYM;
> +				output[j].fields |= PERF_OUTPUT_DSO;
> +				set_print_ip_opts(attr);
> +				goto out;
> +			}
>   		}
>   	}
>