Gerd von Egidy wrote: > Hi, > > I just tried the virtio block device with the intent > to boost disk throughput for my vm. >
We really haven't optimized virtio block yet under KVM. Most of the effort so far has been focused on virtio_net. We'll get there though in the near future. Regards, Anthony Liguori > I ran bonnie++ -r 512 -s 2048 -u nobody -d /tmp: > > Version 1.03 ------Sequential Output------ --Sequential Input- > --Random- > -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- > --Seeks-- > Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec > %CP > virtio_blk 2G 14274 42 20206 14 22363 37 31116 92 66731 81 140.8 > 13 > kvm-ide 2G 26065 83 26435 28 24146 33 26587 84 57991 18 91.5 > 2 > > The host is a Xeon 3040, 1G RAM (I know that that is a bit > few, it's just a test machine...), the vm gets 512MB of that. > The data is stored on two SATA disks, mirrored (RAID1) with > md, lvm running on top of that. > > Host and Client are running 2.6.25-0.200.rc8.git3.i686. This > is a kernel from Fedora-Rawhide with kvm manually enabled by me. > KVM version is 64. > > Especially writing seems to be slower using virtio, but > reading isn't that much faster. > > I thought virtio would improve io speed significantly because > of fewer steps needed to communicate betweeen host and client. > What might be the reason that I can't see a speed boost? > > - Wrong setup (The virtio-client boots from /dev/vda1, > so I think virtio is working) > - virtio_blk is not matured/tuned enough to give a real > speed boost > - I'm missing a patch that is not included into 2.6.26-rc8 > but can be found in kvm-git > - The output of bonnie++ is bogus because timing is not that > accurate within a kvm-client > > Any ideas welcome. > > Kind regards, > > Gerd > > ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
