Message-ID: <424DFF88.30003@yahoo.com.au>
Date: Sat, 02 Apr 2005 12:12:24 +1000
From: Nick Piggin <nickpiggin@yahoo.com.au>
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To: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
CC: "'Ingo Molnar'" <mingo@elte.hu>, "'Linus Torvalds'" <torvalds@osdl.org>,
       "'Andrew Morton'" <akpm@osdl.org>, linux-kernel@vger.kernel.org
Subject: Re: Industry db benchmark result on recent 2.6 kernels
References: <200504020100.j3210fg04870@unix-os.sc.intel.com>
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Chen, Kenneth W wrote:
> Ingo Molnar wrote on Thursday, March 31, 2005 8:52 PM
> 
>>the current defaults for cache_hot_time are 10 msec for NUMA domains,
>>and 2.5 msec for SMP domains. Clearly too low for CPUs with 9MB cache.
>>Are you increasing cache_hot_time in your experiment? If that solves
>>most of the problem that would be an easy thing to fix for 2.6.12.
> 
> 
> 
> Chen, Kenneth W wrote on Thursday, March 31, 2005 9:15 PM
> 
>>Yes, we are increasing the number in our experiments.  It's in the queue
>>and I should have a result soon.
> 
> 
> Hot of the press: bumping up cache_hot_time to 10ms on our db setup brings
> 2.6.11 performance on par with 2.6.9.  Theory confirmed.
> 

OK, that's good. I'll look at whether we can easily use Ingo's
tool on the SMP domain only, to avoid the large O(n^2). That might
be an acceptable short term solution for 2.6.12.

If you get a chance to also look at those block layer patches that
would be good - if they give you a nice improvement, that would
justify getting them into -mm.

-- 
SUSE Labs, Novell Inc.

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