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Date: Fri, 27 Jul 2001 18:42:26 -0300 (BRST)
From: Rik van Riel <riel@conectiva.com.br>
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To: Roger Larsson <roger.larsson@skelleftea.mail.telia.com>
Cc: <linux-kernel@vger.kernel.org>, Linus Torvalds <torvalds@transmeta.com>,
        Daniel Phillips <phillips@kernelnewbies.org>
Subject: Re: 2.4.8-pre1 and dbench -20% throughput
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On Fri, 27 Jul 2001, Roger Larsson wrote:

> But "dbench 32" (on my 256 MB box) results has are the most interesting:
>
> 2.4.0 gave 33 MB/s
> 2.4.8-pre1 gives 26.1 MB/s (-21%)
>
> Do we now throw away pages that would be reused?

Yes. This is pretty much expected behaviour with the use-once
patch, both as it is currently implemented and how it works
in principle.

This is because the use-once strategy protects the working
set from streaming IO in a better way than before. One of the
consequences of this is that streaming IO pages get less of a
chance to be reused before they're evicted.

Database systems usually have a history of recently evicted
pages so they can promote these quick-evicted pages to the
list of more frequently used pages when it's faulted in again.

regards,

Rik
--
Executive summary of a recent Microsoft press release:
   "we are concerned about the GNU General Public License (GPL)"


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