On Fri, 20 Nov 2009 04:39:19 pm Shirley Ma wrote: > Guest virtio_net receives packets from its pre-allocated vring > buffers, then it delivers these packets to upper layer protocols > as skb buffs. So it's not necessary to pre-allocate skb for each > mergable buffer, then frees it when it's useless. > > This patch has deferred skb allocation when receiving packets for > both big packets and mergeable buffers. It reduces skb pre-allocations > and skb_frees. > > Based on Mickael & Avi's suggestion. A destroy function has been created > to push virtio free buffs to vring for unused pages, and used page private > to maintain page list. > > I didn't touch small packet skb allocation to avoid extra copies for small > packets. > > This patch has tested and measured against 2.6.32-rc5 git. It is built again > 2.6.32-rc7 kernel. Tests have been done for small packets, big packets and > mergeable buffers. > > The single netperf TCP_STREAM performance improved for host to guest. > It also reduces UDP packets drop rate. > > The netperf laptop results were: > > mtu=1500 > netperf -H xxx -l 120 > > w/o patch w/i patch (two runs) > guest to host: 3336.84Mb/s 3730.14Mb/s ~ 3582.88Mb/s > > host to guest: 3165.10Mb/s 3370.39Mb/s ~ 3407.96Mb/s Nice! Is this using mergeable_rx_bufs? Or just big_packets? I'd like to drop big packet support from our driver, but I don't know how many kvm hosts will not offer mergable rx bufs yet. Anthony? Thanks, Rusty. -- 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
