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From: | Stuart Anderson |
Subject: | Re: [Qemu-devel] RFC: x86_64 Best way to fix 'cast to pointer from integer of different size' problems? |
Date: | Tue, 6 Nov 2007 16:52:05 -0500 (EST) |
On Tue, 6 Nov 2007, Fabrice Bellard wrote:
Paul Brook wrote:[...] Personally I like the locking interface as it allows a zero-copy implementation. However the kernel uses a copying interface, and my understanding is that other qemu maintainers also prefer the copying interface.At least I don't think it is critical performance wise, especially if the page flag checks are added ! Before you added the current zero copy interface, my plan was to use a zero copy interface just for big buffers such as the one for read/write.
By the time you consider the different combinations of targets & hosts, most of the opportunities for zero copy are eliminated anyway. Byte ordering and structure packing amd content differences mean that we can't do zero-copy except in the rare circumstance that the host & target match is all of these respects. The read & write buffers would still benefit from zero copy, but nearly everything else has to be touched anyway. Stuart Stuart R. Anderson address@hidden Network & Software Engineering http://www.netsweng.com/ 1024D/37A79149: 0791 D3B8 9A4C 2CDC A31F BD03 0A62 E534 37A7 9149
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