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From: Borislav Petkov <bp@alien8.de>
To: Ingo Molnar <mingo@kernel.org>
Cc: "Ghannam, Yazen" <Yazen.Ghannam@amd.com>, x86-ml <x86@kernel.org>,
	Yves Dionne <yves.dionne@gmail.com>,
	Brice Goglin <Brice.Goglin@inria.fr>,
	Peter Zijlstra <peterz@infradead.org>,
	lkml <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH] x86/CPU/AMD: Bring back Compute Unit ID
Date: Thu, 2 Feb 2017 18:04:56 +0100	[thread overview]
Message-ID: <20170202170455.gbuivmli5fhmuucn@pd.tnic> (raw)
In-Reply-To: <20170202160916.GA12498@gmail.com>

On Thu, Feb 02, 2017 at 05:09:16PM +0100, Ingo Molnar wrote:
> If there's any doubt about the validity of the measurement I'd suggest doing:
> 
> 	perf stat -a --sync --repeat 3 ...
> 
> ... so that there's no perf overhead and skew from the many processes of a kernel 
> build workload, plus the --sync should reduce IO related noise.
> 
> Or:
> 
> 	perf stat --null --sync --repeat 3 ...
> 
> ... will only measure elapsed time, but will do that very precisely and with very 
> little overhead.

Yeah, I was talking to Peter about the -a thing on IRC... I think I'm going to
try that. Here's the full command I was using:

./tools/perf/perf stat -e task-clock,context-switches,cache-misses,cpu-migrations,page-faults,cycles,instructions,branches,branch-misses --repeat 3 --sync --pre ~/bin/pre-build-kernel.sh -- make -s -j17 bzImage

I think I stole it from you from some mail thread we had in the past.

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

  reply	other threads:[~2017-02-02 17:05 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-01 20:02 [RFC PATCH] x86/CPU/AMD: Bring back Compute Unit ID Borislav Petkov
2017-02-01 21:37 ` Ghannam, Yazen
2017-02-01 21:44   ` Borislav Petkov
2017-02-01 21:55     ` Ghannam, Yazen
2017-02-01 22:25       ` Borislav Petkov
2017-02-01 22:41         ` Borislav Petkov
2017-02-02 12:10           ` Borislav Petkov
2017-02-02 15:43             ` Borislav Petkov
2017-02-02 16:09               ` Ingo Molnar
2017-02-02 17:04                 ` Borislav Petkov [this message]
2017-02-02 18:10                   ` Borislav Petkov
2017-02-02 20:45                     ` Ghannam, Yazen
2017-02-02 16:14             ` Ghannam, Yazen
2017-02-02 16:29               ` Ingo Molnar

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