On Wednesday 01 April 2009 05:12:47 Gregory Haskins wrote: > Bare metal: tput = 4078Mb/s, round-trip = 25593pps (39us rtt) > Virtio-net: tput = 4003Mb/s, round-trip = 320pps (3125us rtt) > Venet: tput = 4050Mb/s, round-trip = 15255 (65us rtt)
That rtt time is awful. I know the notification suppression heuristic in qemu sucks. I could dig through the code, but I'll ask directly: what heuristic do you use for notification prevention in your venet_tap driver? As you point out, 350-450 is possible, which is still bad, and it's at least partially caused by the exit to userspace and two system calls. If virtio_net had a backend in the kernel, we'd be able to compare numbers properly. > Bare metal: tput = 9717Mb/s, round-trip = 30396pps (33us rtt) > Virtio-net: tput = 4578Mb/s, round-trip = 249pps (4016us rtt) > Venet: tput = 5802Mb/s, round-trip = 15127 (66us rtt) > > Note that even the throughput was slightly better in this test for venet, > though > neither venet nor virtio-net could achieve line-rate. I suspect some tuning > may > allow these numbers to improve, TBD. At some point, the copying will hurt you. This is fairly easy to avoid on xmit tho. Cheers, Rusty. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
