linux-kernel - Re: [PATCH 06/14] perf tools: show NMI overhead

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Date:   Wed, 23 Nov 2016 23:51:51 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     kan.liang@...el.com
Cc:     peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
        linux-kernel@...r.kernel.org, alexander.shishkin@...ux.intel.com,
        tglx@...utronix.de, namhyung@...nel.org, jolsa@...nel.org,
        adrian.hunter@...el.com, wangnan0@...wei.com, mark.rutland@....com,
        andi@...stfloor.org
Subject: Re: [PATCH 06/14] perf tools: show NMI overhead

On Wed, Nov 23, 2016 at 04:44:44AM -0500, kan.liang@...el.com wrote:
> From: Kan Liang <kan.liang@...el.com>
> 
> Caculate the total NMI overhead on each CPU, and display them in perf
> report

so the output looks like this:

---
# Elapsed time: 1720167944 ns
# Overhead:
#       CPU 6
#               NMI#: 27 time: 111379 ns
#               Multiplexing#: 0 time: 0 ns
#               SB#: 57 time: 90045 ns
#
# Samples: 26  of event 'cycles:u'
# Event count (approx.): 1677531
#
# Overhead  Command  Shared Object     Symbol                 
# ........  .......  ................  .......................
#
    24.20%  ls       ls                [.] _init
    17.18%  ls       libc-2.24.so      [.] __strcoll_l
    11.85%  ls       ld-2.24.so        [.] _dl_relocate_object
---


few things:

- I wonder we want to put this overhead output separatelly from the
  main perf out.. this scale bad with with bigger cpu counts

- we might want to call it some other way, becayse we already
  use 'overhead' for the event count %

- how about TUI output? ;-) I dont think it's necessary, however
  currently 'perf report --show-overhead' does not show anything
  ifTUI is default output, unless you use --stdio option

thanks,
jirka