From: Tony Luck <tony.luck@gmail.com>
To: Andrew Morton <akpm@osdl.org>
Cc: eranian@hpl.hp.com, linux-kernel@vger.kernel.org,
perfmon@napali.hpl.hp.com, linux-ia64@vger.kernel.org,
perfctr-devel@lists.sourceforge.net
Subject: Re: quick overview of the perfmon2 interface
Date: Tue, 20 Dec 2005 18:05:11 +0000 [thread overview]
Message-ID: <12c511ca0512201005k4d499b57v724815258f80322@mail.gmail.com> (raw)
In-Reply-To: <20051220025156.a86b418f.akpm@osdl.org>
> > The interface also supports automatic randomization of the reset value
> > for a PMD after an overflow.
>
> Why would one want to randomise the PMD after an overflow?
To get better data. Using a constant reload value may keep measuring the
same spot in the application if you are using a sample frequency that
matches some repeat pattern in the application (and Murphy's law says
that you'll hit this a lot).
-Tony
next prev parent reply other threads:[~2005-12-20 18:05 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-12-19 11:31 quick overview of the perfmon2 interface Stephane Eranian
2005-12-20 10:51 ` Andrew Morton
2005-12-20 11:19 ` [Perfctr-devel] " Mikael Pettersson
2005-12-20 18:05 ` Tony Luck [this message]
2005-12-20 18:16 ` Stephane Eranian
2005-12-20 23:52 ` David Gibson
2005-12-22 11:56 ` Stephane Eranian
2005-12-22 12:05 ` Christoph Hellwig
2005-12-22 15:37 ` [Perfctr-devel] " William Cohen
2005-12-22 17:23 ` Christoph Hellwig
2005-12-22 18:17 ` William Cohen
2005-12-22 18:36 ` John Reiser
2005-12-22 18:48 ` [perfmon] " Stephane Eranian
2005-12-21 22:39 ` Truong, Dan
2005-12-22 13:31 ` Truong, Dan
2005-12-22 13:46 ` Andrew Morton
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