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Created attachment 493728[details]
rhel6.1-snp1-vhost-net vs virtio-net megabyte/cpu
Description of problem:
1> When application doesn't flow control, megabyte/cpu shows regression (drop ) for all UDP R for guest to host.Detail info ,please check the attachment.
2> When application does flow control, for example by rate-limiting the stream to within 10% and 30% packet drops, vhost-net doesn't have performance improvement for UDP R for guest to host compared with virtio-net.
Lost packet rate = 10%
vhost-net
Socket Message Elapsed Messages
Size Size Time Okay Errors Throughput
bytes bytes secs # # 10^6bits/sec
124928 1460 60.00 468000 0 91.10
124928 60.00 420001 81.76
virtio-net
Socket Message Elapsed Messages
Size Size Time Okay Errors Throughput
bytes bytes secs # # 10^6bits/sec
124928 1460 60.00 468000 0 91.10
124928 60.00 420003 81.76
Lost packet rate = 30%
vhost-net
Socket Message Elapsed Messages
Size Size Time Okay Errors Throughput
bytes bytes secs # # 10^6bits/sec
124928 1460 60.00 600000 0 116.80
124928 60.00 420122 81.78
virtio-net
Socket Message Elapsed Messages
Size Size Time Okay Errors Throughput
bytes bytes secs # # 10^6bits/sec
124928 1460 60.00 600000 0 116.80
124928 60.00 420029 81.77
Version-Release number of selected component (if applicable):
host:
kernel-2.6.32-125.el6.x86_64
qemu-kvm-0.12.1.2-2.152.el6.x86_64
guest:
kernel-2.6.32-125.el6.x86_64
How reproducible:
Steps to Reproduce:
1.steps for description 1
run netserver on the guest
run netperf ci on the host like : mpstat -P ALL 1 &>${CPU_FILE} & ssh $client $client_path -C -c -H $server -l 30 -t UDP_STREAM -- -m $packet_size && kill -9 `pgrep mpstat`
Calculate megabyte/cpu for each packets sizes
2.steps for description 2
Rate limit the sender and see at what rate of sender do you get some predefined loss ratio (e.g control the lost packet rate within 10% and 30%).
configurate netperf with "--enable-intervals=yes "
Lost packet rate = 10%
vhost-net:/root/tool/netperf-2.4.5/src/netperf -w 1 -b 78 -H 192.168.0.13 -l 60 -t UDP_STREAM -- -m 1460
virtio-net:/root/tool/netperf-2.4.5/src/netperf -w 1 -b 78 -H 192.168.0.13 -l60 -t UDP_STREAM -- -m 1460
Lost packet rate = 30%
vhost-net:/root/tool/netperf-2.4.5/src/netperf -w 1 -b 100 -H 192.168.0.13 -l 60 -t UDP_STREAM -- -m 1460
virtio-net:/root/tool/netperf-2.4.5/src/netperf -w 1 -b 100 -H 192.168.0.13 -l 60 -t UDP_STREAM -- -m 1460
Actual results:
Expected results:
Additional info:
Comment 2Michael S. Tsirkin
2011-05-30 15:40:21 UTC
Basically I think to improve UDP receive speed we need something like GRO for UDP. Another thing that is reported to help here is the event index
feature. In both cases we need the code upstream first as
maintaining a forked version in rhel would be very painful.
Re-tested it on latest rhel7 host/guest with 3.10.0-138.el7.x86_64/qemu-kvm-1.5.3-66.el7.x86_64
From atteched file UDP_Rhel7-3.10.0-138.html, we could see :
- for samll packet ( <= 4096), 0% packet drop in both virtio-net/vhost, but host sends more UDP through virtio-net than vhost, so there is 20% around degradation through vhost.
- for large packet ( > 4096), although host sends more (around 20%) UDP through virtio-net than vhost, but guest receive UDP more through vhost than virtio-net.
Vlad, any comments about above results, do you think we still have UDP issue with vhost?
Created attachment 493728 [details] rhel6.1-snp1-vhost-net vs virtio-net megabyte/cpu Description of problem: 1> When application doesn't flow control, megabyte/cpu shows regression (drop ) for all UDP R for guest to host.Detail info ,please check the attachment. 2> When application does flow control, for example by rate-limiting the stream to within 10% and 30% packet drops, vhost-net doesn't have performance improvement for UDP R for guest to host compared with virtio-net. Lost packet rate = 10% vhost-net Socket Message Elapsed Messages Size Size Time Okay Errors Throughput bytes bytes secs # # 10^6bits/sec 124928 1460 60.00 468000 0 91.10 124928 60.00 420001 81.76 virtio-net Socket Message Elapsed Messages Size Size Time Okay Errors Throughput bytes bytes secs # # 10^6bits/sec 124928 1460 60.00 468000 0 91.10 124928 60.00 420003 81.76 Lost packet rate = 30% vhost-net Socket Message Elapsed Messages Size Size Time Okay Errors Throughput bytes bytes secs # # 10^6bits/sec 124928 1460 60.00 600000 0 116.80 124928 60.00 420122 81.78 virtio-net Socket Message Elapsed Messages Size Size Time Okay Errors Throughput bytes bytes secs # # 10^6bits/sec 124928 1460 60.00 600000 0 116.80 124928 60.00 420029 81.77 Version-Release number of selected component (if applicable): host: kernel-2.6.32-125.el6.x86_64 qemu-kvm-0.12.1.2-2.152.el6.x86_64 guest: kernel-2.6.32-125.el6.x86_64 How reproducible: Steps to Reproduce: 1.steps for description 1 run netserver on the guest run netperf ci on the host like : mpstat -P ALL 1 &>${CPU_FILE} & ssh $client $client_path -C -c -H $server -l 30 -t UDP_STREAM -- -m $packet_size && kill -9 `pgrep mpstat` Calculate megabyte/cpu for each packets sizes 2.steps for description 2 Rate limit the sender and see at what rate of sender do you get some predefined loss ratio (e.g control the lost packet rate within 10% and 30%). configurate netperf with "--enable-intervals=yes " Lost packet rate = 10% vhost-net:/root/tool/netperf-2.4.5/src/netperf -w 1 -b 78 -H 192.168.0.13 -l 60 -t UDP_STREAM -- -m 1460 virtio-net:/root/tool/netperf-2.4.5/src/netperf -w 1 -b 78 -H 192.168.0.13 -l60 -t UDP_STREAM -- -m 1460 Lost packet rate = 30% vhost-net:/root/tool/netperf-2.4.5/src/netperf -w 1 -b 100 -H 192.168.0.13 -l 60 -t UDP_STREAM -- -m 1460 virtio-net:/root/tool/netperf-2.4.5/src/netperf -w 1 -b 100 -H 192.168.0.13 -l 60 -t UDP_STREAM -- -m 1460 Actual results: Expected results: Additional info: