linux-kernel - Re: Discrepancies between Oprofile and vmstat II

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Message-ID: <20090427222242.GJ27382@one.firstfloor.org>
Date:	Tue, 28 Apr 2009 00:22:42 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	"Styner, Douglas W" <douglas.w.styner@...el.com>
Cc:	Andi Kleen <andi@...stfloor.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"oprofile-list@...ts.sf.net" <oprofile-list@...ts.sf.net>,
	"Ma, Chinang" <chinang.ma@...el.com>,
	"willy@...ux.intel.com" <willy@...ux.intel.com>
Subject: Re: Discrepancies between Oprofile and vmstat II

On Mon, Apr 27, 2009 at 03:15:27PM -0700, Styner, Douglas W wrote:
> 
> > I believe so, but will confirm.
> >
> > > opcontrol -e=CPU_CLK_UNHALTED:80000 -e=LLC_MISSES:6000
> > > 
> > > Using another profiling tool to confirm, we see 74.784% user, 25.174% > > kernel.
> >
> > Just verifying -- you also see it when you use a shorter period than 80000 > right?
> 
> Confirmed.  Changes in profile appear to be due to increased sampling by oprofile with lower value.

You mean "with higher value", right ?

It's still strange that it suddenly changed in 2.6.27 though. There shouldn't have been
a difference there. So I still think it's a regression.

-Andi
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