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

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Date:   Thu, 24 Nov 2016 13:37:04 +0000
From:   "Liang, Kan" <kan.liang@...el.com>
To:     Jiri Olsa <jolsa@...hat.com>
CC:     "peterz@...radead.org" <peterz@...radead.org>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "acme@...nel.org" <acme@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "alexander.shishkin@...ux.intel.com" 
        <alexander.shishkin@...ux.intel.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "namhyung@...nel.org" <namhyung@...nel.org>,
        "jolsa@...nel.org" <jolsa@...nel.org>,
        "Hunter, Adrian" <adrian.hunter@...el.com>,
        "wangnan0@...wei.com" <wangnan0@...wei.com>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "andi@...stfloor.org" <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
> 
This output can only be shown when the user explicitly apply
the --show-overhead option. I think the user should expect the big
header.
Or I can add  --show-overhead-only option which only show the
overhead information. It will like what we do for --header and
--header-only 

Any suggestions?

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

"operating_cost"? "processing_cost"? "perf_cost"? "perf_overhead"?
Suggestions?
 
> - 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

I will try to add something in TUI mode.

Thanks,
Kan