From mboxrd@z Thu Jan 1 00:00:00 1970 From: Udo Lembke Subject: kvm io-performance with smp Date: Fri, 30 Apr 2010 08:38:59 +0200 Message-ID: <4BDA7B03.2050806@polarzone.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit To: kvm@vger.kernel.org Return-path: Received: from mailgate.abc-digital.com ([62.206.40.27]:47216 "EHLO mailgate.albertbauer.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758206Ab0D3RX2 (ORCPT ); Fri, 30 Apr 2010 13:23:28 -0400 Received: from localhost (localhost [127.0.0.1]) by mailgate.albertbauer.com (Postfix) with ESMTP id 2069814AD2 for ; Fri, 30 Apr 2010 08:39:00 +0200 (CEST) Sender: kvm-owner@vger.kernel.org List-ID: 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 "|" 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