i hope this topic isn't discuss several times before but i found no similiar posting with the search-function.
I use kvm with proxmox ve and kvm work very well, but the io-performance with windows-guests is only good with one (guest)cpu.
The testings are based on kvm 0.12.3 (with the same result on 0.11.1).
Here is my posting, that i post in the proxmox-forum. But nobody has a solution there.
after a lot more tests (on another node, with faster raid and the raid only for the vm)...
It seems that the IO-performance under windows with smp depends on fortune (or luck, or what else). If only run the IO-Prozess the values are sometimes not so bad, but if there another process, like the task-manager to show the cpu usage, the io-performance be worse. Up to very worse. I've got a notion that the performance drop if the io-process change the cpu (often).
It's happens with the 2.6.32 and also with the 2.6.24 kernel (I don't test the 2.6.18 yet).
Here the test-results (h2benchw -p -w 2cp_th_2.6.32_v1 2; profile install) on a virtio-disk (virtio-driver 18.104.22.16841) :
all values MB/s - different runs seperate with "|"
1 CPU 2.6.32: 488
1 CPU aio=threads 2.6.32: 517 | 573 | 569
2 CPU aio=threads 2.6.32: 333 | 78 | 28
2 CPU aio=native 2.6.32: 101 | 128 | 53
2 CPU aio=threads 2.6.32: 215 | 66 | 103 | 179 | 26 | 58 | 109
2 CPU aio=native 2.6.32: 70 | 39 | 3.7| 14
2 CPU aio=threads 2.6.24: 298 | 47 | 27 | 121 | 120 | 82 | 104
2 CPU cache=none 2.6.24: 55 | 92 | 102 | 114 | open task-manager: 67
Perhaps there are other switches for kvm to solve this problem?
My test kvm:
/usr/bin/kvm -monitor unix:/var/run/qemu-server/126.mon,server,nowait -vnc unix:/var/run/qemu-server/126.vnc,password -pidfile /var/run/qemu-server/126.pid -daemonize -usbdevice tablet -name knecht2 -smp sockets=2,cores=1 -nodefaults -boot menu=on,order=c -vga cirrus -tdf -localtime -rtc-td-hack -k de -drive file=/var/lib/vz/template/iso/vm-tools.iso,if=ide,index=1,media=cdrom -drive file=/var/lib/vz/images/126/vm-126-disk-1.raw,if=ide,index=0,boot=on -drive file=/var/lib/vz/images/126/vm-126-disk-2.raw,if=ide,index=2 -drive file=/var/lib/vz/images/126/vm-126-disk-3.raw,if=virtio,index=0,aio=threads -m 1024 -net tap,vlan=0,ifname=vmtab126i0,script=/var/lib/qemu-server/bridge-vlan -net nic,vlan=0,model=e1000,macaddr=F6:E1:E2:E4:93:4E
I will be quite happy, if someone has a hint for me.