From mboxrd@z Thu Jan 1 00:00:00 1970 From: Reeted Subject: Re: [libvirt] Qemu/KVM is 3x slower under libvirt Date: Wed, 28 Sep 2011 11:49:01 +0200 Message-ID: <4E82ED8D.10004@shiftmail.org> References: <4E82118D.2010702@shiftmail.org> <20110928075138.GC21102@redhat.com> <4E82E6AF.5070009@shiftmail.org> <20110928092859.GO21102@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; format=flowed; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, libvir-list@redhat.com To: "Daniel P. Berrange" Return-path: Received: from blade3.isti.cnr.it ([194.119.192.19]:64802 "EHLO BLADE3.ISTI.CNR.IT" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751151Ab1I1Jta (ORCPT ); Wed, 28 Sep 2011 05:49:30 -0400 Received: from [192.168.7.52] (firewall.itb.cnr.it [155.253.6.254]) by mx.isti.cnr.it (PMDF V6.5-x5 #31918) with ESMTPSA id <01O6L392UXIAXZN4IA@mx.isti.cnr.it> for kvm@vger.kernel.org; Wed, 28 Sep 2011 11:49:01 +0200 (MEST) In-reply-to: <20110928092859.GO21102@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 09/28/11 11:28, Daniel P. Berrange wrote: > On Wed, Sep 28, 2011 at 11:19:43AM +0200, Reeted wrote: >> On 09/28/11 09:51, Daniel P. Berrange wrote: >>>> This is my bash commandline: >>>> >>>> /opt/qemu-kvm-0.14.1/bin/qemu-system-x86_64 -M pc-0.14 -enable-kvm >>>> -m 2002 -smp 2,sockets=2,cores=1,threads=1 -name vmname1-1 -uuid >>>> ee75e28a-3bf3-78d9-3cba-65aa63973380 -nodefconfig -nodefaults >>>> -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/vmname1-1.monitor,server,nowait >>>> -mon chardev=charmonitor,id=monitor,mode=readline -rtc base=utc >>>> -boot order=dc,menu=on -drive file=/dev/mapper/vgPtpVM-lvVM_Vmname1_d1,if=none,id=drive-virtio-disk0,boot=on,format=raw,cache=none,aio=native >>>> -device virtio-blk-pci,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0 >>>> -drive if=none,media=cdrom,id=drive-ide0-1-0,readonly=on,format=raw,cache=none,aio=native >>>> -device ide-drive,bus=ide.1,unit=0,drive=drive-ide0-1-0,id=ide0-1-0 >>>> -net nic,model=virtio -net tap,ifname=tap0,script=no,downscript=no >>>> -usb -vnc 127.0.0.1:0 -vga cirrus -device >>>> virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x5 >>> This shows KVM is being requested, but we should validate that KVM is >>> definitely being activated when under libvirt. You can test this by >>> doing: >>> >>> virsh qemu-monitor-command vmname1 'info kvm' >> kvm support: enabled >> >> I think I would see a higher impact if it was KVM not enabled. >> >>>> Which was taken from libvirt's command line. The only modifications >>>> I did to the original libvirt commandline (seen with ps aux) were: > >>>> - Network was: -netdev tap,fd=17,id=hostnet0,vhost=on,vhostfd=18 >>>> -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:05:36:60,bus=pci.0,addr=0x3 >>>> Has been simplified to: -net nic,model=virtio -net >>>> tap,ifname=tap0,script=no,downscript=no >>>> and manual bridging of the tap0 interface. >>> You could have equivalently used >>> >>> -netdev tap,ifname=tap0,script=no,downscript=no,id=hostnet0,vhost=on >>> -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:05:36:60,bus=pci.0,addr=0x3 >> It's this! It's this!! (thanks for the line) >> >> It raises boot time by 10-13 seconds > Ok, that is truely bizarre and I don't really have any explanation > for why that is. I guess you could try 'vhost=off' too and see if that > makes the difference. YES! It's the vhost. With vhost=on it takes about 12 seconds more time to boot. ...meaning? :-)