linux-kernel - RE: [PATCH V2 04/13] perf/core: output multiplexing overhead

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Message-ID: <37D7C6CF3E00A74B8858931C1DB2F07750CA9EBB@SHSMSX103.ccr.corp.intel.com>
Date:   Tue, 6 Dec 2016 15:04:48 +0000
From:   "Liang, Kan" <kan.liang@...el.com>
To:     Peter Zijlstra <peterz@...radead.org>
CC:     "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 V2 04/13] perf/core: output multiplexing overhead



> On Fri, Dec 02, 2016 at 04:19:12PM -0500, kan.liang@...el.com wrote:
> > From: Kan Liang <kan.liang@...el.com>
> >
> > Multiplexing overhead is one of the key overhead when the number of
> > events is more than available counters.
> >
> > The multiplexing overhead PERF_CORE_MUX_OVERHEAD is a common
> overhead
> > type.
> >
> 
> > diff --git a/include/uapi/linux/perf_event.h
> > b/include/uapi/linux/perf_event.h index fe7b1fb..355086f 100644
> > --- a/include/uapi/linux/perf_event.h
> > +++ b/include/uapi/linux/perf_event.h
> > @@ -999,6 +999,7 @@ struct perf_branch_entry {
> >   */
> >  enum perf_record_overhead_type {
> >  	PERF_CORE_OVERHEAD	 = 0,
> > +	PERF_CORE_MUX_OVERHEAD	 = 0,
> 
> '0' already had a name ?!

PERF_CORE_OVERHEAD is only used to indicate the start of core
overhead type.
I will use comment line to replace PERF_CORE_OVERHEAD. 

Thanks,
Kan