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Date: Mon, 05 Nov 2001 00:37:55 -0800
From: Andrew Morton <akpm@zip.com.au>
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To: Robert Love <rml@tech9.net>
CC: Zwane Mwaikambo <zwane@linux.realnet.co.sz>, linux-kernel@vger.kernel.org
Subject: Re: 2.4.13-ac5-preempt, overflow in cached memory stat?
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Robert Love wrote:
> 
> > PS I know you keep hearing this, but that preempt patch makes for some
> > damn smooth interactive performance ;)
> 
> I can't hear it enough :)
> 

umm...  Look.  Sorry.  But I don't see any theoretical reason
why interactivity should be noticeably different from the
little patch at

http://www.kernel.org/pub/linux/kernel/people/andrea/kernels/v2.4/2.4.14pre7aa2/00_lowlatency-fixes-2

and I did some quantitative testing a week or so back which
bears this out.  With either patch, worst-case latencies
are very rare, and very bad.   Usual latencies are excellent.

Is there any reason why preempt should be noticeably better than
that little patch?  If it is, then where on earth are the
problematic commonly-occuring, long-running, lock-free code paths?

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