On 12/04/2011 05:11 PM, Michael S. Tsirkin wrote: > > There's also the used ring, but that's a > > mistake if you have out of order completion. We should have used copying. > > Seems unrelated... unless you want used to be written into > descriptor ring itself?
The avail/used rings are in addition to the regular ring, no? If you copy descriptors, then it goes away. > But, I don't really know why does virtio ring insist on > making the 3 buffers (avail/used/descriptor) > physically contigious. Rusty? Let's drop them instead. > > > 16kB worth of descriptors is 1024 entries. With 4kB buffers, that's 4MB > > worth of data, or 4 ms at 10GbE line speed. With 1500 byte buffers it's > > just 1.5 ms. In any case I think it's sufficient. > > Right. So I think that without indirect, we waste about 3 entries > per packet for virtio header and transport etc headers. That does suck. Are there issues in increasing the ring size? Or making it discontiguous? Can you take a peek at how Xen manages its rings? They have the same problems we do. -- error compiling committee.c: too many arguments to function _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
