On Sun, Dec 04, 2011 at 02:06:34PM +0200, Avi Kivity wrote: > On 12/04/2011 02:01 PM, Michael S. Tsirkin wrote: > > > > > > How much better? > > > > > > I think that if indirects benefit networking, then we're doing something > > > wrong. What's going on? Does the ring get filled too early? If so we > > > should expand it. > > > > The ring is physically contigious. > > With 256 entries and 64 bytes each, that's already 16K. > > A descriptor is just 16 bytes. Right. Not sure where did I get 64. > 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? But, I don't really know why does virtio ring insist on making the 3 buffers (avail/used/descriptor) physically contigious. Rusty? > 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. > -- > error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
