Re: [PATCH 0/4] perf report: add parameters 'start' & 'end' to specify analysis interval

[Ingo Molnar <mingo@kernel.org>]

* Chenggang Qin <chenggang.qin@gmail.com> wrote:

> This patch set introduced a feature to analysis the samples in a specified time
> interval.
> After perf.data file was generated by perf record, the user could want to
> analysis a sub time interval of the whole record period.
> For some functions, the percent of its samples in a certain sub time interval is
> different from the percent in the total record period. Showing the scene in a
> certain time interval could allow users to more easily troubleshoot performance
> problems. The sample's timestamp are recorded in the perf.data file. The samples
> are sorted in the ordered_samples by timestamp while perf report processed them.
> So, it is easily to search the samples whose timestamp are in a certain time
> interval.
> We add 2 paramters --start and --end to specify the time interval.
> perf report --start xxxxx --end xxxxx
> The smallest granularity of time interval is millsecond.
> For example:
> If the whole record period of a perf.data file is 10000 to 20000, we can use the
> following command to analysis the samples between [15000, 16000).
> perf report --start 15000 --end 16000
> The time is the uptime, it start timing from the system starts.
> 
> Cc: David Ahern <dsahern@gmail.com>
> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
> Cc: Arjan van de Ven <arjan@linux.intel.com>
> Cc: Namhyung Kim <namhyung@gmail.com>
> Cc: Yanmin Zhang <yanmin.zhang@intel.com>
> Cc: Wu Fengguang <fengguang.wu@intel.com>
> Cc: Mike Galbraith <efault@gmx.de>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Chenggang Qin <chenggang.qcg@taobao.com>
> 
> Chenggang Qin (4):
>   perf tools: add parameter 'start' & 'end' to perf report
>   perf tools: relate 'start' & 'end' to perf_session
>   perf tools: record min_timestamp of samples queue in ordered_samples
>   perf tools: add the feature to assign analysis interval to perf
>     report
> 
>  tools/perf/builtin-report.c |   14 ++++++++++++
>  tools/perf/util/session.c   |   49 +++++++++++++++++++++++++++++++++++++++++-
>  tools/perf/util/session.h   |    3 ++
>  3 files changed, 64 insertions(+), 2 deletions(-)

Looks useful - but right now this has to be used 'blindly', without 
knowing _which_ portion of the perf.data is 'interesting'.

That problem could be resolved by allowing direct manipulation of 
the start/end interval via the GTK front end: a small graph could 
show the 'sample graph', with two sliders specifying the reported 
interval?

Something like this, at the top of the window:

  ---------------------------------------------------------------
  |                                                             |
  |    ....                        .....                        |
  | ..      .            ...    .         .                     |
  |          .       ...    .  .            .    .              |
  |            .....         ..               ..  .... .... ..  |
  |                          [1]             [2]                |
  ---------------------------------------------------------------
  |
  |   Usual perf report GTK output
  |
  |   ....
  |

The 'graph' might be anything that visualizes the time axis of the 
perf.data: a sample frequency visualization for example, or maybe a 
simple task activity graph based on fork/exec/exit data, with some 
simple time display included as well (a vertical marker every 
minute/second or so).

The [1] and [2] markers demark the two sliders, which in the above 
mockup example show an 'interesting' portion of the profile with a 
lot of samples.

With such a solution the feature you add would be very useful 
indeed, I'd even argue for the data file time-axis visualization to 
be enabled by default, with the initial start/end interval covering 
the whole perf.data, but the sliders being just a mouse-drag away 
from being changed.

Thanks,

	Ingo