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From: | Anthony Liguori |
Subject: | Re: [kvm-devel] [Qemu-devel] [PATCH 1/5] PCI DMA API (v3) |
Date: | Sun, 20 Apr 2008 14:29:43 -0500 |
User-agent: | Thunderbird 2.0.0.12 (X11/20080227) |
Blue Swirl wrote:
On 4/19/08, Anthony Liguori <address@hidden> wrote:Well, the IOVector part and bdrv_readv look OK, except for the heavymallocing involved.
I don't think that in practice, malloc is going to have any sort of performance impact. If it does, it's easy enough to implement a small object allocator for common, small vector sizes.
I'm not so sure about the DMA side and how everything fits together for zero-copy IO. For example, do we still need explicit translation at some point?
I'm thinking that zero copy will be implemented by setting the map and unmap functions to NULL by default (instead of to the PCI read/write functions). Then the bus can decide whether copy functions are needed. I'll send an updated patch series tomorrow that includes this functionality.
Regards, Anthony Liguori
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