Andrew Olney wrote: > I've been migrating from Xen to KVM for a wide variety of reasons. > > I've noticed, however, that XP installs much much faster with Xen (3.03 > xen-image-xen0-2.6.17-6-generic-xen0 ubuntu) than with KVM (14). > > I haven't clocked it, but for KVM it takes longer than realtime (by the > XP install clock) and with Xen it takes less than realtime. > > I assume that this is all file I/O related, which raises the question: > what file system setup optimizes KVM I/O, e.g. qcow vs. raw? >
Xen should outperform KVM wrt disk performance. Xen is based on QEMU 0.8.2 and has a ton of patches including one that aggressive reports IO completions to the host asynchronously. KVM uses a version of QEMU that is significantly closer to mainline QEMU (almost no changes that aren't KVM related). Eventually, all of the KVM changes should make it into mainline QEMU whereas that probably will never happen with Xen. QEMU only got asynchronous IO support in 0.9.0. Unfortunately, the implementation actually results in a regression in performance. Some hacks can fix it though. Of course, the SCSI emulation in 0.9.0 improves performance by quite a lot (to the point where it's better than Xen). However, some work is needed to make SCSI disks bootable and to expose SCSI command line options. Regards, Anthony Liguori > ------------------------------------------------------------------------- > Take Surveys. Earn Cash. Influence the Future of IT > Join SourceForge.net's Techsay panel and you'll get the chance to share your > opinions on IT & business topics through brief surveys-and earn cash > http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV > _______________________________________________ > kvm-devel mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/kvm-devel > > ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ kvm-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/kvm-devel
