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Date:      Wed, 17 Nov 2010 22:53:38 -0500
From:      George Neville-Neil <gnn@neville-neil.com>
To:        Andriy Gapon <avg@FreeBSD.org>
Cc:        freebsd-acpi@freebsd.org, freebsd-current@freebsd.org
Subject:   Re: aperf/mperf
Message-ID:  <D1DB20AD-779E-469B-BFFA-C0BA1A249858@neville-neil.com>
In-Reply-To: <4CE29718.2050508@freebsd.org>
References:  <4CE29718.2050508@freebsd.org>

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On Nov 16, 2010, at 09:37 , Andriy Gapon wrote:

>=20
> Many modern processors provide APERF and MPERF MSRs which allow to =
easily and
> reliable calculate average CPU performance level over some interval of =
time.
> This also allows to notice things like performance boost, which is =
generally
> hidden from software.
> What would be a proper place to add code that would measure =
APERF/MPERF ratio?
> When should trigger such a measurement and over what interval?
> Ideas?

Can you point me at documentation for this?   This sounds a lot like
hwpmc(4) and I wonder if we can make these available in the same way.

Best,
George




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