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Date:	Thu, 12 Oct 2006 17:20:52 -0700
From:	"Chen, Kenneth W" <kenneth.w.chen@...el.com>
To:	"'Dave Jones'" <davej@...hat.com>
Cc:	"'Zach Brown'" <zach.brown@...cle.com>,
	"'Suparna Bhattacharya'" <suparna@...ibm.com>,
	"Lahaise, Benjamin C" <benjamin.c.lahaise@...el.com>,
	<linux-kernel@...r.kernel.org>, "linux-aio" <linux-aio@...ck.org>
Subject: RE: [patch] rearrange kioctx and aio_ring_info

Dave Jones wrote on Thursday, October 12, 2006 5:04 PM
> On Thu, Oct 12, 2006 at 04:25:54PM -0700, Chen, Kenneth W wrote:
>  > The following patch is result of our kernel data latency analysis on a
>  > large database setup (128 logical CPU, 1 TB memory, a couple thousand
>  > disks). The analysis is done at an individual cache line level through
>  > hardware performance monitor unit.  What we did essentially is to collect
>  > data access latency on every kernel memory address and look for top 50
>  > longest average access latency.  The hardware performance unit also keeps
>  > track of instruction address for each collected data access.  This allows
>  > us to further associate each of the top 50 cache lines to instruction
>  > sequences that caused long latency.
> 
> Do you have performance numbers of before/after this change ?


Not yet, I just queued up experiment on our internal benchmark setup. I posted
the patch here to get some early discussion on how to attack the problem.
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