Aurelien Jarno wrote: > On Wed, May 07, 2008 at 04:40:58PM -0500, Anthony Liguori wrote: > >> The current logic of the can_receive handler is to allow packets whenever the >> receiver is disabled or when there are descriptors available in the ring. >> >> I think the logic ought to be to allow packets whenever the receiver is >> enabled >> and there are descriptors available in the ring. >> > > The current behaviour is actually correct, this is the way QEMU works: > when the card is stopped, it should always accept packets, and then > discard them. >
The previous patches in my virtio series change that behavior. Before delivering a packet to a VLAN, it checks to see if any of the VLAN clients are able to receive a packet. This is very important for achieving good performance with tap. With virtio-net, we were dropping a ton of packets with tap because there weren't descriptors available on the RX ring. I plan to submit that behavioral change to QEMU upstream along with the virtio drivers. I'm still optimizing phys_page_find() though. The performance impact of switching the ring manipulation to using the stl_phys accessors is unacceptable for KVM. Regards, Anthony Liguori ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
