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Date: Tue, 13 Feb 2007 11:27:58 +0000
From: Alan <alan@lxorguk.ukuu.org.uk>
To: Arjan van de Ven <arjan@infradead.org>
Cc: "Martin A. Fink" <fink@mpe.mpg.de>, Matthias Schniedermeyer <ms@citd.de>,
       linux-kernel@vger.kernel.org
Subject: Re: SATA-performance: Linux vs. FreeBSD
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> there's several tunables you can do;
> 1) increase /sys/block/<device>/queue/nr_requests
>    the linux default is on the low side
> 5) echo a larger value into /sys/block/<device>/queue/max_sectors_kb
>    the default seems to be 512 which is... really low. The hw max is in
>    another file in that directory; if you want max throughput set the
>    max_sectors_kb value to the hw max. (you pay in terms of fairness for


There are two more factors that play into #1 and #5. Firstly there is a
per command completion overhead in ATA without NCQ being active and that
isn't yet a heavily optimised libata path. Secondly erase block size
matters with flash drives so the bigger each I/O the better erase block
behaviour we should get.
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