Re: [PATCH 10/12] kvm: enable smp 1
Avi Kivity schrieb: On 05/19/2010 11:02 PM, Udo Lembke wrote: Unrelated, what are your smp issues? If i use one cpu i got a good io-performance: e.g. over 500MB/s at the profile install of the io-benchmark h2benchw.exe. ( aio=threads | SAS-Raid-0 | ftp://ftp.heise.de/pub/ct/ctsi/h2benchw.zip | hwbenchw.exe -p -w iotest 0) The same test but with two cpus gives results between 27 and 298 MB/s! Also in real life it's noticeable not only with an benchmark. I use a win-vm with two cpu for postscript-ripping and have a performance drop due to the bad io. Hi, What's your block device model? virtio or ide? in the test described before i used virtio, but the same happens with ide (but of course slightly different values). What does cpu usage look like on guest or host? On the guest it's looks like the io-process flap between the cpus. Windows show both cpus together are around 65% (less or more) , but if one CPU-usage rise, the other drop. On the host: PID USER PR NI VIRT RES SHR S %CPU %MEMTIME+ COMMAND 5386 root 20 0 1160m 1.0g 1552 R 109 13.5 1:23.58 kvm The guest is a win-xp, but the same happens in real life on a win2003. Udo smime.p7s Description: S/MIME Cryptographic Signature
Re: [PATCH 10/12] kvm: enable smp 1
Jan Kiszka schrieb: ... --enable-io-thread? If you had it disabled, it would also answer my question if -smp works without problems without that feature. Jan Hi, i have a dumb question: what is the --enable-io-thread? Is this a kvm-switch? My kvm 0.12.4 don't accept this switch. I'm know only threads=n as smp-parameter and aio=threads as drive-parameter. Because i look for a solution for a better io-performance of windows-guest with more than one cpu... best regards Udo smime.p7s Description: S/MIME Cryptographic Signature
Re: [PATCH 10/12] kvm: enable smp 1
Avi Kivity schrieb: On 05/19/2010 12:57 PM, Udo Lembke wrote: Jan Kiszka schrieb: ... --enable-io-thread? If you had it disabled, it would also answer my question if -smp works without problems without that feature. Jan Hi, i have a dumb question: what is the --enable-io-thread? Is this a kvm-switch? It's a ./configure switch for upstream qemu (don't use with qemu-kvm yet). My kvm 0.12.4 don't accept this switch. I'm know only threads=n as smp-parameter and aio=threads as drive-parameter. Because i look for a solution for a better io-performance of windows-guest with more than one cpu... Unrelated, what are your smp issues? If i use one cpu i got a good io-performance: e.g. over 500MB/s at the profile install of the io-benchmark h2benchw.exe. ( aio=threads | SAS-Raid-0 | ftp://ftp.heise.de/pub/ct/ctsi/h2benchw.zip | hwbenchw.exe -p -w iotest 0) The same test but with two cpus gives results between 27 and 298 MB/s! Also in real life it's noticeable not only with an benchmark. I use a win-vm with two cpu for postscript-ripping and have a performance drop due to the bad io. Udo -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
kvm io-performance with smp
Hello, i'm new on this list and hope this topic isn't discuss several times before. 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 there know a solution. Hi, 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 4.3.0.17241) : all values MB/s - different runs seperate with | http://forums.meulie.net/viewtopic.php?f=43t=6136sid=79fe2173580718169824cb2e454a3efa#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. Best regards Udo -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
