linux-kernel - Re: [PATCH RFC 1/1] perf,tool: partial callgrap and time support

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Date:	Tue, 30 Jun 2015 14:34:59 +0200
From:	Jiri Olsa <jolsa@...hat.com>
To:	kan.liang@...el.com
Cc:	acme@...nel.org, namhyung@...nel.org, jolsa@...nel.org,
	ak@...ux.intel.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC 1/1] perf,tool: partial callgrap and time support

On Sun, Jun 28, 2015 at 01:47:21PM -0400, kan.liang@...el.com wrote:
> From: Kan Liang <kan.liang@...el.com>
> 
> When multiple events are sampled it may not be needed to collect
> callgraphs for all of them. The sample sites are usually nearby, and
> it's enough to collect the callgraphs on a reference event (such as
> precise cycles or precise instructions). Similarly we also don't need
> fine grained time stamps on all events, as it's enough to have time
> stamps on the regular reference events.
> This patchkit adds the ability to turn off callgraphs and time stamps
> per event. This in term can reduce sampling overhead and the size of the
> perf.data. Furthermore, it makes collecting back traces and timestamps
> possible when PEBS threshold > 1, which significantly reducing the
> sampling overhead especially for frequently occurring events
> (https://lkml.org/lkml/2015/5/10/196). For example, A slower event with
> a larger period collects back traces/timestamps. Other more events run
> fast with multi-pebs. The time stamps from the slower events can be used
> to order the faster events. Their backtraces can give the user enough
> hint to find the right spot.

SNIP

> 
>      7.13%     0.03%  tchain_edit  [kernel.vmlinux]  [k] do_nmi
>             |
>             ---do_nmi
>                end_repeat_nmi
>                f3
>                f2
>                f1
>                main
>                __libc_start_main
> 
> Signed-off-by: Kan Liang <kan.liang@...el.com>
> ---
>  tools/perf/Documentation/perf-record.txt | 13 ++++++++
>  tools/perf/builtin-record.c              |  7 ++--
>  tools/perf/perf.h                        |  2 ++
>  tools/perf/util/evsel.c                  | 55 ++++++++++++++++++++++++++++++--
>  tools/perf/util/parse-events.c           | 33 +++++++++++++++++++
>  tools/perf/util/parse-events.h           |  3 ++
>  tools/perf/util/parse-events.l           |  3 ++
>  tools/perf/util/parse-options.c          |  2 ++
>  tools/perf/util/parse-options.h          |  4 +++
>  9 files changed, 116 insertions(+), 6 deletions(-)

could you please break up this patch into:
  - parse option changes (+description what are those new macros  good for)
  - callchains terms addition
  - time term addition

thanks,
jirka
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