>-----Original Message----- >From: Shirley Ma [mailto:mashirle@xxxxxxxxxx] >Sent: Friday, July 30, 2010 6:31 AM >To: Xin, Xiaohui >Cc: netdev@xxxxxxxxxxxxxxx; kvm@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; >mst@xxxxxxxxxx; mingo@xxxxxxx; davem@xxxxxxxxxxxxx; herbert@xxxxxxxxxxxxxxxxxxx; >jdike@xxxxxxxxxxxxxxx >Subject: Re: [RFC PATCH v8 00/16] Provide a zero-copy method on KVM virtio-net. > >Hello Xiaohui, > >On Thu, 2010-07-29 at 19:14 +0800, xiaohui.xin@xxxxxxxxx wrote: >> The idea is simple, just to pin the guest VM user space and then >> let host NIC driver has the chance to directly DMA to it. >> The patches are based on vhost-net backend driver. We add a device >> which provides proto_ops as sendmsg/recvmsg to vhost-net to >> send/recv directly to/from the NIC driver. KVM guest who use the >> vhost-net backend may bind any ethX interface in the host side to >> get copyless data transfer thru guest virtio-net frontend. > >Since vhost-net already supports macvtap/tun backends, do you think >whether it's better to implement zero copy in macvtap/tun than inducing >a new media passthrough device here? > >> Our goal is to improve the bandwidth and reduce the CPU usage. >> Exact performance data will be provided later. > >I did some vhost performance measurement over 10Gb ixgbe, and found that >in order to get consistent BW results, netperf/netserver, qemu, vhost >threads smp affinities are required. > >Looking forward to these results for small message size comparison. For >large message size 10Gb ixgbe BW already reached by doing vhost smp >affinity w/i offloading support, we will see how much CPU utilization it >can be reduced. > >Please provide latency results as well. I did some experimental on >macvtap zero copy sendmsg, what I have found that get_user_pages latency >pretty high. > May you share me with your performance results (including BW and latency)on vhost-net and how you get them(your configuration and especially with the affinity settings)? Thanks Xiaohui >Thanks >Shirley > > > -- 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
