linux-kernel - Re: [PATCH 1/2] perf report: Support --header-only for pipe mode

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Date:   Mon, 14 Dec 2020 00:00:19 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Namhyung Kim <namhyung@...nel.org>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Stephane Eranian <eranian@...gle.com>,
        Ian Rogers <irogers@...gle.com>
Subject: Re: [PATCH 1/2] perf report: Support --header-only for pipe mode

On Thu, Dec 10, 2020 at 03:13:01PM +0900, Namhyung Kim wrote:
> The --header-only checks file header and prints the feature data.  But
> as pipe mode doesn't have it in the header it prints almost nothing.
> Change it to process first few records until it founds HEADER_FEATURE.
> 
> Before:
>   $ perf record -o- true | perf report -i- --header-only
>   # ========
>   # captured on    : Thu Dec 10 14:34:59 2020
>   # header version : 1
>   # data offset    : 0
>   # data size      : 0
>   # feat offset    : 0
>   # ========
>   #
> 
> After:
>   $ perf record -o- true | perf report -i- --header-only
>   # ========
>   # captured on    : Thu Dec 10 14:49:11 2020
>   # header version : 1
>   # data offset    : 0
>   # data size      : 0
>   # feat offset    : 0
>   # ========
>   #
>   # hostname : balhae
>   # os release : 5.7.17-1xxx
>   # perf version : 5.10.rc6.gdb0ea13cc741
>   # arch : x86_64
>   # nrcpus online : 8
>   # nrcpus avail : 8
>   # cpudesc : Intel(R) Core(TM) i7-8665U CPU @ 1.90GHz
>   # cpuid : GenuineIntel,6,142,12
>   # total memory : 16158916 kB
>   # cmdline : perf record -o- true
>   # event : name = cycles, , id = { 81, 82, 83, 84, 85, 86, 87, 88 }, size = 120, ...
>   # CPU_TOPOLOGY info available, use -I to display
>   # NUMA_TOPOLOGY info available, use -I to display
>   # pmu mappings: intel_pt = 9, intel_bts = 8, software = 1, power = 20, uprobe = 7, ...
>   # time of first sample : 0.000000
>   # time of last sample : 0.000000
>   # sample duration :      0.000 ms
>   # MEM_TOPOLOGY info available, use -I to display
>   # cpu pmu capabilities: branches=32, max_precise=3, pmu_name=skylake
> 
> Signed-off-by: Namhyung Kim <namhyung@...nel.org>

Acked-by: Jiri Olsa <jolsa@...hat.com>

thanks,
jirka

> ---
>  tools/perf/builtin-report.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
> index 5efbd0602f17..2a845d6cac09 100644
> --- a/tools/perf/builtin-report.c
> +++ b/tools/perf/builtin-report.c
> @@ -226,6 +226,8 @@ static int process_feature_event(struct perf_session *session,
>  		pr_err("failed: wrong feature ID: %" PRI_lu64 "\n",
>  		       event->feat.feat_id);
>  		return -1;
> +	} else if (rep->header_only) {
> +		session_done = 1;
>  	}
>  
>  	/*
> @@ -1512,6 +1514,13 @@ int cmd_report(int argc, const char **argv)
>  		perf_session__fprintf_info(session, stdout,
>  					   report.show_full_info);
>  		if (report.header_only) {
> +			if (data.is_pipe) {
> +				/*
> +				 * we need to process first few records
> +				 * which contains PERF_RECORD_HEADER_FEATURE.
> +				 */
> +				perf_session__process_events(session);
> +			}
>  			ret = 0;
>  			goto error;
>  		}
> -- 
> 2.29.2.576.ga3fc446d84-goog
>