Avi Kivity <avi <at> redhat.com> writes: > > On 03/15/2010 03:23 PM, Anthony Liguori wrote: > > On 03/15/2010 08:11 AM, Avi Kivity wrote: > >> Your guest wasn't doing a zillion VMREADs and VMWRITEs every exit. > >> > >> I plan to reduce VMREAD/VMWRITE overhead for kvm, but not much we can > >> do for other guests. > > > > VMREAD/VMWRITEs are generally optimized by hypervisors as they tend to > > be costly. KVM is a bit unusual in terms of how many times the > > instructions are executed per exit. > > Do you know offhand of any unnecessary read/writes? There's > update_cr8_intercept(), but on normal exits, I don't see what else we > can remove. > In comparing KVM 2.6.31.6b to XenServer 5.5.0, it seems KVM has fewer overall VMREADs and VMWRITEs, but there are a lot of VMWRITEs to Host FS_SEL, Host GS_SEL, Host FS_BASE, and Host GS_BASE that don't appear in Xen. Also, KVM has a lot of MSR accesses to 0xc0000081-0xc0000084 that Xen doesn't have. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
