Avi Kivity wrote: > Nakajima, Jun wrote: >> I compared the performance on Xen and KVM for kernel build using the >> same guest image. Looks like KVM was (kvm-17) three times slower as >> far as we tested, and that high load of qemu was one of the >> symptoms. We are looking at the shadow code, but the load of qemu >> looks very high. I remember we had similar problems in Xen before, >> but those were fixed. Someone should take a look at the qemu side. >> > > I'd expect the following issues to dominate: > > - the shadow cache is quite small at 256 pages. Increasing it may > increase performance.
Yes, we are aware of this. > > - we haven't yet taught the scheduler that migrating vcpus is > expensive due to the IPI needed to fetch the vmcs. Maybe running > with 'taskset 1' would help > > - shadow eviction policy is FIFO, not LRU, which probably causes many > page faults. This may explain that the performance gets worse as we repeat kernel build, at least, the second run is slower than the first one. > > Running kvm_stat can help show what's going on. Thanks for the good insights. We'll come back with some analysis. Jun --- Intel Open Source Technology Center ------------------------------------------------------------------------- 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 kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
