linux-kernel - Re: Mainline kernel OLTP performance update

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Date:	Wed, 29 Apr 2009 10:28:25 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	"Styner, Douglas W" <douglas.w.styner@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Tripathi, Sharad C" <sharad.c.tripathi@...el.com>,
	"arjan@...ux.intel.com" <arjan@...ux.intel.com>,
	"Wilcox, Matthew R" <matthew.r.wilcox@...el.com>,
	"Kleen, Andi" <andi.kleen@...el.com>,
	"Siddha, Suresh B" <suresh.b.siddha@...el.com>,
	"Ma, Chinang" <chinang.ma@...el.com>,
	"Wang, Peter Xihong" <peter.xihong.wang@...el.com>,
	"Nueckel, Hubert" <hubert.nueckel@...el.com>,
	"Recalde, Luis F" <luis.f.recalde@...el.com>,
	"Nelson, Doug" <doug.nelson@...el.com>,
	"Cheng, Wu-sun" <wu-sun.cheng@...el.com>,
	"Prickett, Terry O" <terry.o.prickett@...el.com>,
	"Shunmuganathan, Rajalakshmi" <rajalakshmi.shunmuganathan@...el.com>,
	"Garg, Anil K" <anil.k.garg@...el.com>,
	"Chilukuri, Harita" <harita.chilukuri@...el.com>,
	"chris.mason@...cle.com" <chris.mason@...cle.com>
Subject: Re: Mainline kernel OLTP performance update

Andrew Morton <akpm@...ux-foundation.org> writes:

>> ======oprofile CPU_CLK_UNHALTED for top 30 functions
>> Cycles% 2.6.24.2                   Cycles% 2.6.30-rc3
>> 74.8578 <database>                 69.1925 <database>
>
> ouch, that's a large drop in userspace CPU occupancy.  It seems
> inconsistent with the 1.91% above.

That was determined to be an oprofile artifact/regression (see Doug's
other email+thread) The 2.6.30 oprofile seems to be less accurate than
the one in 2.6.24. Of course the question is if it can't get
the user space right, is the kernel data accurate. But I believe
Doug verified with vtune that the kernel data is roughly correct,
just user space profiling was slightly bogus (right, Doug, or
do I misrepresent that?)

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only.
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