Messages in this thread | | | Date | Mon, 21 May 2001 12:27:53 +0200 | From | Andi Kleen <> | Subject | Re: alpha iommu fixes |
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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.
[BTW, the 2.4.4 netstack does not seem to make any attempt to handle the pagecache > 4GB case on IA32 for sendfile, as the pci_* functions are dummies here. It probably needs bounce buffers there for this case]
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