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From: Pierre Ossman <drzeus-list@drzeus.cx>
To: Russell King <rmk+lkml@arm.linux.org.uk>
Cc: LKML <linux-kernel@vger.kernel.org>
Subject: Re: Choosing scatter/gather limits
Date: Wed, 13 Oct 2004 14:48:06 +0200	[thread overview]
Message-ID: <416D2406.1040002@drzeus.cx> (raw)
In-Reply-To: <20041013122234.A23105@flint.arm.linux.org.uk>

Russell King wrote:

>On Mon, Oct 11, 2004 at 12:53:23PM +0200, Pierre Ossman wrote:
>  
>
>>I've been adding scatter/gather support for the MMC host driver I'm 
>>writing. I cannot find any documentation on how to chose the limits though.
>>    
>>
>
>It seems that you have to read the block layer code to find out what's
>going on with these limits.  There's some documentation on it in
>Documentation/block/bio.txt.  If it's lacking, then please send
>comments to the block layer people to add the necessary information.
>
>  
>
I just wanted to make sure I don't pick values that causes problems 
somewhere else. I'll make an attempt to dig through the bio code though.

>Please also note that I'm intending to make the MMC host drivers
>know nothing about block IO stuff, so all you'll be passed is the
>MMC commands and a scatter gather list - so making sure that your
>driver always uses blk_rq_map_sg() and works from the SG list will
>ensure that your driver remains easy to update.
>
>  
>
Shouldn't be a problem. The SGIO support in the driver is done. Just 
need to get rid of all bugs.

Rgds
Pierre



      reply	other threads:[~2004-10-13 12:48 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-10-11 10:53 Choosing scatter/gather limits Pierre Ossman
2004-10-13 11:22 ` Russell King
2004-10-13 12:48   ` Pierre Ossman [this message]

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