Open Stack

Hi deal stackers,

I am running a devstack with two nodes:
one is controller (no nova-compute running) and other is compute.

I am using neutron ml2 plugin and ovs agent with GRE tunnel.

I started a VM and tried to run iperf testing:
1. start iperf as server role in the VM, which has a floating ip
192.168.10.10:
iperf -s

2 start iperf as client role on the controler node to test the VM via
floating ip:
iperf -c 192.168.10.10 -t 120

at the same time, run top on compute node, I found the vhost-{pid} was
taking too much cpu resource ( more than 75%):

Tasks: 230 total,   2 running, 228 sleeping,   0 stopped,   0 zombie
%Cpu0  : 23.7 us,  9.1 sy,  0.0 ni, 66.9 id,  0.0 wa,  0.0 hi,  0.3 si,
 0.0 st
%Cpu1  : 10.2 us,  2.7 sy,  0.0 ni, 86.3 id,  0.0 wa,  0.0 hi,  0.7 si,
 0.0 st
%Cpu2  :  0.0 us, 19.8 sy,  0.0 ni,  5.2 id,  0.0 wa,  2.2 hi, 72.8 si,
 0.0 st
%Cpu3  : 12.6 us,  4.2 sy,  0.0 ni, 83.2 id,  0.0 wa,  0.0 hi,  0.0 si,
 0.0 st
KiB Mem:  12264832 total,  1846428 used, 10418404 free,    43692 buffers
KiB Swap:        0 total,        0 used,        0 free,   581572 cached

  PID USER      PR  NI  VIRT  RES  SHR S  %CPU %MEM    TIME+  COMMAND

 4073 root      20   0     0    0    0 R  79.8  0.0   3:26.97 vhost-4070


gongysh at gongysh-p6535cn:~$ ps -ef | grep 4070
119       4070     1 31 19:24 ?        00:04:13 qemu-system-x86_64 -machine
accel=kvm:tcg -name instance-00000002 -S -M pc-i440fx-1.4 -m 2048 -smp
1,sockets=1,cores=1,threads=1 -uuid 5cbfb914-d16c-4b51-a057-50f2da827830
-smbios type=1,manufacturer=OpenStack Foundation,product=OpenStack
Nova,version=2014.1,serial=94b43180-e901-1015-b061-90cecbca80a3,uuid=5cbfb914-d16c-4b51-a057-50f2da827830
-no-user-config -nodefaults -chardev
socket,id=charmonitor,path=/var/lib/libvirt/qemu/instance-00000002.monitor,server,nowait
-mon chardev=charmonitor,id=monitor,mode=control -rtc
base=utc,driftfix=slew -no-hpet -no-shutdown -device
piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive
file=/opt/stack/data/nova/instances/5cbfb914-d16c-4b51-a057-50f2da827830/disk,if=none,id=drive-virtio-disk0,format=qcow2,cache=none
-device
virtio-blk-pci,scsi=off,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1
-drive
file=/opt/stack/data/nova/instances/5cbfb914-d16c-4b51-a057-50f2da827830/disk.config,if=none,id=drive-ide0-1-1,readonly=on,format=raw,cache=none
-device ide-cd,bus=ide.1,unit=1,drive=drive-ide0-1-1,id=ide0-1-1 -netdev
tap,fd=23,id=hostnet0,vhost=on,vhostfd=24 -device
virtio-net-pci,netdev=hostnet0,id=net0,mac=fa:16:3e:ce:da:ae,bus=pci.0,addr=0x3
-chardev
file,id=charserial0,path=/opt/stack/data/nova/instances/5cbfb914-d16c-4b51-a057-50f2da827830/console.log
-device isa-serial,chardev=charserial0,id=serial0 -chardev
pty,id=charserial1 -device isa-serial,chardev=charserial1,id=serial1 -vnc
0.0.0.0:0 -k en-us -vga cirrus -device
virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x5


This is a big performance problem, imagine almost all the cpu resources
will be consumed by the vhost-{pid}s if we have many VMs and all are
running with full speed network traffic.


any ideas?

regards,
yong sheng gong
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