Messages in this thread | | | Date | Tue, 22 May 2001 00:22:27 +0200 | From | Jens Axboe <> | Subject | Re: alpha iommu fixes |
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On Mon, May 21 2001, Andi Kleen wrote: > On Mon, May 21, 2001 at 03:00:24AM -0700, David S. Miller wrote: > > > That's currently the case, but at least on IA32 the block layer > > > must be fixed soon because it's a serious performance problem in > > > some cases (and fixing it is not very hard). > > > > If such a far reaching change goes into 2.4.x, I would probably > > begin looking at enhancing the PCI dma interfaces as needed ;-) > > Hmm, I don't think it'll be a far reaching change. As far as I can see > all it needs is a new entry point for block device drivers that uses > bh->b_page. When that entry point exists skip the create_bounce call > in __make_request. After that it is purely problem for selected drivers.
I've already done it, however not as a 2.4 solution. The partial and WIP patches is here:
*.kernel.org/pub/linux/kernel/people/axboe/v2.5/bio-7
Block driver can indicate the need for bounce buffers above a certain page.
Of course I can hack up something for 2.4 as well, but is this really a pressing need?
-- Jens Axboe
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