Hi all, I have been testing network throughput and latency and I was wondering if my measurements are as expected. For the test, I used Fedora 17 for both host and guest, using kernel 3.5.2-3.fc17.86_64. Pinging an external server on the LAN from the host, using a gigabit interface, the results are: # ping -c 10 172.16.1.1 PING 172.16.1.1 (172.16.1.1) 56(84) bytes of data. 64 bytes from 172.16.1.1: icmp_req=1 ttl=64 time=0.109 ms 64 bytes from 172.16.1.1: icmp_req=2 ttl=64 time=0.131 ms 64 bytes from 172.16.1.1: icmp_req=3 ttl=64 time=0.145 ms 64 bytes from 172.16.1.1: icmp_req=4 ttl=64 time=0.116 ms 64 bytes from 172.16.1.1: icmp_req=5 ttl=64 time=0.110 ms 64 bytes from 172.16.1.1: icmp_req=6 ttl=64 time=0.114 ms 64 bytes from 172.16.1.1: icmp_req=7 ttl=64 time=0.112 ms 64 bytes from 172.16.1.1: icmp_req=8 ttl=64 time=0.117 ms 64 bytes from 172.16.1.1: icmp_req=9 ttl=64 time=0.119 ms 64 bytes from 172.16.1.1: icmp_req=10 ttl=64 time=0.128 ms --- 172.16.1.1 ping statistics --- 10 packets transmitted, 10 received, 0% packet loss, time 8999ms rtt min/avg/max/mdev = 0.109/0.120/0.145/0.011 ms Pinging the same external host on the LAN from the guest, the latency seems to be much higher: # ping -c 10 172.16.1.1 PING 172.16.1.1 (172.16.1.1) 56(84) bytes of data. 64 bytes from 172.16.1.1: icmp_req=1 ttl=64 time=0.206 ms 64 bytes from 172.16.1.1: icmp_req=2 ttl=64 time=0.352 ms 64 bytes from 172.16.1.1: icmp_req=3 ttl=64 time=0.518 ms 64 bytes from 172.16.1.1: icmp_req=4 ttl=64 time=0.351 ms 64 bytes from 172.16.1.1: icmp_req=5 ttl=64 time=0.543 ms 64 bytes from 172.16.1.1: icmp_req=6 ttl=64 time=0.387 ms 64 bytes from 172.16.1.1: icmp_req=7 ttl=64 time=0.348 ms 64 bytes from 172.16.1.1: icmp_req=8 ttl=64 time=0.364 ms 64 bytes from 172.16.1.1: icmp_req=9 ttl=64 time=0.345 ms 64 bytes from 172.16.1.1: icmp_req=10 ttl=64 time=0.334 ms --- 172.16.1.1 ping statistics --- 10 packets transmitted, 10 received, 0% packet loss, time 8999ms rtt min/avg/max/mdev = 0.206/0.374/0.543/0.093 ms The LAN, the host and guest are idle otherwise during the tests. There are no iptables rules active. The vhost_net and macvtap modules are loaded on the host, and qemu was started (by libvirtd) with the -netdev vhost=on option. The guest is using the virtio_net driver. Is this expected and normal, or do others see better latencies? Can I try anything to make it better? Thanks, Balazs Pozsar -- 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
