From: Ingo Molnar <mingo@kernel.org>
To: Borislav Petkov <bp@alien8.de>
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 17:09:16 +0100 [thread overview]
Message-ID: <20170202160916.GA12498@gmail.com> (raw)
In-Reply-To: <20170202154359.fevz4fmwc6t4ew75@pd.tnic>
* Borislav Petkov <bp@alien8.de> wrote:
> On Thu, Feb 02, 2017 at 01:10:54PM +0100, Borislav Petkov wrote:
> > Now on to run the same thing on a bigger bulldozer.
>
> It looks differently on the bigger box:
>
> before:
>
> Performance counter stats for 'make -s -j17 bzImage' (3 runs):
> 143.807894000 seconds time elapsed ( +- 0.89% )
>
> Performance counter stats for 'make -s -j17 bzImage' (3 runs):
> 147.109189694 seconds time elapsed ( +- 0.49% )
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.
Thanks,
Ingo
next prev parent reply other threads:[~2017-02-02 16:10 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 [this message]
2017-02-02 17:04 ` Borislav Petkov
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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