Re: [PATCH 3/5] aacraid: update dma mapping

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On Wed, 2005-11-30 at 12:45 -0600, James Bottomley wrote:
> On Wed, 2005-11-30 at 10:36 -0800, Mark Haverkamp wrote:
> > This patch changes map_single to map_page in compliance with
> > recommendations made in the IO-Perf howto document to prevent bounce
> > buffering of DMA requests.
> 
> Erm, there's a misunderstanding somewhere.  You're replacing correct
> pci_map_single calls with its more difficult to use pci_map_page.  This
> has absolutely zero performance impact and adds the risk that because
> pci_map_page is more complex to use, someone gets it wrong somewhere.
> Really, for block devices pci_map_single is the absolutely correct
> interface.  pci_map_page should really only be used by the net stack for
> packet fragment mapping.

Thanks,  The remaining patches still apply cleanly without it.

Mark.


> 
> James
> 
-- 
Mark Haverkamp <markh@xxxxxxxx>

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