Messages in this thread | | | Subject | RE: [PATCH] [scsi] Remove __GFP_DMA | Date | Wed, 23 May 2007 15:17:08 -0400 | From | "Salyzyn, Mark" <> |
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The 31 bit limit for some of these cards is a problem, we currently only do __GFP_DMA for bounce buffer sg elements allocated for user supplied references in ioctls.
I figure we should be using pci_alloc_consistent calls for these allocations to more accurately acquire memory within the 31 bit limit if necessary, we could switch to these to remove the need for the __GFP_DMA flag in the aacraid driver?
-- Mark
-----Original Message----- From: linux-scsi-owner@vger.kernel.org [mailto:linux-scsi-owner@vger.kernel.org] On Behalf Of James Bottomley Sent: Wednesday, May 23, 2007 11:18 AM To: Aubrey Li Cc: Christoph Lameter; Bernhard Walle; linux-scsi@vger.kernel.org; Andrew Morton; linux-kernel@vger.kernel.org Subject: Re: [PATCH] [scsi] Remove __GFP_DMA
On Wed, 2007-05-23 at 10:41 +0800, Aubrey Li wrote: > On 5/23/07, Christoph Lameter <clameter@sgi.com> wrote: > > On Mon, 21 May 2007, Bernhard Walle wrote: > > > > > [PATCH] [scsi] Remove __GFP_DMA > > > > > > After 821de3a27bf33f11ec878562577c586cd5f83c64, it's not necessary to alloate a > > > DMA buffer any more in sd.c. > > > > > > Signed-off-by: Bernhard Walle <bwalle@suse.de> > > > > Great that avoids a DMA kmalloc slab. Any other GFP_DMAs left in the scsi > > layer? > > > > Acked-by: Christoph Lameter <clameter@sgi.com> > > Yes, here is another patch
I'll defer to Mark on this one. However, please remember that you can't just blindly remove GFP_DMA ... there are some cards which require it.
Aacraid is one example ... it has a set of cards that can only DMA to 31 bits. For them, the GFP_DMA is necessary: The allocation in question is a scatterlist, which must be within the device DMA mask.
James
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