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Date: Thu, 18 Apr 2002 16:48:55 -0700
From: Andrew Morton <akpm@zip.com.au>
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To: Alan Cox <alan@lxorguk.ukuu.org.uk>
CC: Mark Peloquin <peloquin@us.ibm.com>, linux-kernel@vger.kernel.org
Subject: Re: Bio pool & scsi scatter gather pool usage
In-Reply-To: <OFCF00F1A4.2665039D-ON85256B9F.006B755C@pok.ibm.com> from "Mark Peloquin" at Apr 18, 2002 05:58:16 PM <E16yLS4-0005vN-00@the-village.bc.nu>
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Alan Cox wrote:
> 
> > Perhaps, but calls are expensive. Repeated calls down stacked block
> > devices will add up. In only the most unusually cases will there
> 
> You don't need to repeatedly query. At bind time you can compute the
> limit for any device heirarchy and be done with it.
> 

S'pose so.  The ideal request size is variable, based
on the alignment.  So for exampe if the start block is
halfway into a stripe, the ideal BIO size is half a stripe.

But that's a pretty simple table to generate once-off,
as you say.

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