Message-ID: <41637BD5.7090001@yahoo.com.au>
Date: Wed, 06 Oct 2004 15:00:05 +1000
From: Nick Piggin <nickpiggin@yahoo.com.au>
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To: Andrew Morton <akpm@osdl.org>
CC: kenneth.w.chen@intel.com, mingo@redhat.com, linux-kernel@vger.kernel.org,
       Judith Lebzelter <judith@osdl.org>
Subject: Re: Default cache_hot_time value back to 10ms
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Andrew Morton wrote:

> This tunable caused an 11% performance difference in (I assume) TPCx. 
> That's a big deal, and people will want to diddle it.
> 

True. But 2.5 I think really is too low (for anyone, except maybe a
CPU with no/a tiny L2 cache).

> If one number works optimally for all machines and workloads then fine.
> 

Yeah.. 10ms may bring up idle times a bit on other workloads. Judith
had some database tests that were very sensitive to this - if 10ms is
OK there, then I'd say it would be OK for most things.

> But yes, avoiding a tunable would be nice, but we need a tunable to work
> out whether we can avoid making it tunable ;)
> 

Heh. I think it would be good to have a automatic thingy to tune it.
A smarter cache_decay_ticks calculation would suit.

> Not that I'm soliciting patches or anything.  I'll duck this one for now.
> 

OK. Any idea when 2.6.9 will be coming out? :)
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