linux-kernel - Re: [PATCH RESEND] perf record: Add --buildid-all option

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Message-ID: <5694F166.3000401@intel.com>
Date:	Tue, 12 Jan 2016 14:28:22 +0200
From:	Adrian Hunter <adrian.hunter@...el.com>
To:	Namhyung Kim <namhyung@...nel.org>,
	Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Jiri Olsa <jolsa@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Andi Kleen <andi@...stfloor.org>,
	Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH RESEND] perf record: Add --buildid-all option

On 11/01/16 15:38, Namhyung Kim wrote:
> The --buildid-all option is to record build-id of all DSOs in the file.
> It might be very costly to postprocess samples to find which DSO hits.
>
> Cc: Adrian Hunter <adrian.hunter@...el.com>
> Cc: Andi Kleen <andi@...stfloor.org>
> Cc: Stephane Eranian <eranian@...gle.com>
> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> ---
>  tools/perf/Documentation/perf-record.txt |  3 +++
>  tools/perf/builtin-record.c              | 32 ++++++++++++++++++++++++++------
>  2 files changed, 29 insertions(+), 6 deletions(-)
>
> diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
> index 3a1a32f5479f..fbceb631387c 100644
> --- a/tools/perf/Documentation/perf-record.txt
> +++ b/tools/perf/Documentation/perf-record.txt
> @@ -338,6 +338,9 @@ Options passed to clang when compiling BPF scriptlets.
>  Specify vmlinux path which has debuginfo.
>  (enabled when BPF prologue is on)
>  
> +--buildid-all::
> +Record build-id of all DSOs regardless whether it's actually hit or not.
> +
>  SEE ALSO
>  --------
>  linkperf:perf-stat[1], linkperf:perf-list[1]
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index dc4e0adf5c5b..a42cb2955697 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -50,6 +50,7 @@ struct record {
>  	int			realtime_prio;
>  	bool			no_buildid;
>  	bool			no_buildid_cache;
> +	bool			buildid_all;
>  	unsigned long long	samples;
>  };
>  
> @@ -362,6 +363,13 @@ static int process_buildids(struct record *rec)
>  	 */
>  	symbol_conf.ignore_vmlinux_buildid = true;
>  
> +	/*
> +	 * If --buildid-all is given, it marks all DSO regardless of hits,
> +	 * so no need to process samples.
> +	 */
> +	if (rec->buildid_all)
> +		rec->tool.sample = NULL;

I wonder, if we are not processing samples, could the processing could be
much simpler?
All we need to do is read all the MMAP events, in any order, and create DSOs
- no need to
create threads or map-groups etc etc.