Tim Chen wrote: > Hi, > > I did some testing of KVM on my woodcrest machine. And I found that > building a 2.6.19 kernel with identical configuration takes 845 sec on a > guest and 210 sec on the host. So the compile is about 4X slower on the > guest :( > > The guest ran with 2.6.19 kernel and host ran with a 2.6.20-rc5 kernel. > The guest file image is created with raw format. Wonder if people see > similar performance figure? > >
http://virt.kernelnewbies.org/KVM/Performance cites a 2.5X difference, but for a different cpu. It's probably better to use an lvm volume rather than a raw file, and to give the guest ample memory. In addition, quite a few performance optimizations are missing from kvm: - after modifying a pte, kvm doesn't preload the modified pte into shadow, but instead lets the guest fault it in - disk access is blocking instead of non-blocking. this will be fixed by merging qemu-cvs, which uses aio for disk access. - better heuristics for recycling page tables are needed - prefaulting for common access patterns can help - kvm currently saves the entire fpu state on every exit, even if it has not been modified -- Do not meddle in the internals of kernels, for they are subtle and quick to panic. ------------------------------------------------------------------------- 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
