Public bug reported: Hi, I boot a guest with "-netdev tap,id=hn0,vhost=off,br=br0,helper=/usr/local/libexec/qemu-bridge- helper" network option, and using "netperf -H IP -t UDP_STREAM" to test guest UDP performance, I got the following output:
Socket Message Elapsed Messages Size Size Time Okay Errors Throughput bytes bytes secs # # 10^6bits/sec 212992 65507 10.00 144710 0 7583.56 212992 10.00 32 1.68 We can find most of UDP packets are lost. But I test another host machine or use "-netdev usr,xxxxx". I can got: Socket Message Elapsed Messages Size Size Time Okay Errors Throughput bytes bytes secs # # 10^6bits/sec 212992 65507 10.00 18351 0 961.61 212992 10.00 18350 961.56 most of UDP packets are recived. And If we check the tap qemu used, we can see: ifconfig tap0 tap0: flags=4419<UP,BROADCAST,RUNNING,PROMISC,MULTICAST> mtu 1500 inet6 fe80::ecc6:21ff:fe6f:b174 prefixlen 64 scopeid 0x20<link> ether ee:c6:21:6f:b1:74 txqueuelen 1000 (Ethernet) RX packets 282 bytes 30097 (29.3 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 9086214 bytes 12731596673 (11.8 GiB) TX errors 0 dropped 16349024 overruns 0 carrier 0 collisions 0 lots of TX packets are dropped. list other packet size: ➜ boot netperf -H 192.168.199.200 -t UDP_STREAM -- -m 1 MIGRATED UDP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.199.200 () port 0 AF_INET Socket Message Elapsed Messages Size Size Time Okay Errors Throughput bytes bytes secs # # 10^6bits/sec 212992 1 10.00 2297941 0 1.84 212992 10.00 1462024 1.17 ➜ boot netperf -H 192.168.199.200 -t UDP_STREAM -- -m 128 MIGRATED UDP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.199.200 () port 0 AF_INET Socket Message Elapsed Messages Size Size Time Okay Errors Throughput bytes bytes secs # # 10^6bits/sec 212992 128 10.00 2311547 0 236.70 212992 10.00 1359834 139.25 ** Affects: qemu Importance: Undecided Status: New -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1920871 Title: netperf UDP_STREAM high packet loss on QEMU tap network Status in QEMU: New Bug description: Hi, I boot a guest with "-netdev tap,id=hn0,vhost=off,br=br0,helper=/usr/local/libexec/qemu-bridge- helper" network option, and using "netperf -H IP -t UDP_STREAM" to test guest UDP performance, I got the following output: Socket Message Elapsed Messages Size Size Time Okay Errors Throughput bytes bytes secs # # 10^6bits/sec 212992 65507 10.00 144710 0 7583.56 212992 10.00 32 1.68 We can find most of UDP packets are lost. But I test another host machine or use "-netdev usr,xxxxx". I can got: Socket Message Elapsed Messages Size Size Time Okay Errors Throughput bytes bytes secs # # 10^6bits/sec 212992 65507 10.00 18351 0 961.61 212992 10.00 18350 961.56 most of UDP packets are recived. And If we check the tap qemu used, we can see: ifconfig tap0 tap0: flags=4419<UP,BROADCAST,RUNNING,PROMISC,MULTICAST> mtu 1500 inet6 fe80::ecc6:21ff:fe6f:b174 prefixlen 64 scopeid 0x20<link> ether ee:c6:21:6f:b1:74 txqueuelen 1000 (Ethernet) RX packets 282 bytes 30097 (29.3 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 9086214 bytes 12731596673 (11.8 GiB) TX errors 0 dropped 16349024 overruns 0 carrier 0 collisions 0 lots of TX packets are dropped. list other packet size: ➜ boot netperf -H 192.168.199.200 -t UDP_STREAM -- -m 1 MIGRATED UDP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.199.200 () port 0 AF_INET Socket Message Elapsed Messages Size Size Time Okay Errors Throughput bytes bytes secs # # 10^6bits/sec 212992 1 10.00 2297941 0 1.84 212992 10.00 1462024 1.17 ➜ boot netperf -H 192.168.199.200 -t UDP_STREAM -- -m 128 MIGRATED UDP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.199.200 () port 0 AF_INET Socket Message Elapsed Messages Size Size Time Okay Errors Throughput bytes bytes secs # # 10^6bits/sec 212992 128 10.00 2311547 0 236.70 212992 10.00 1359834 139.25 To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1920871/+subscriptions