On Wed, 4 Jul 2012 23:09:10 -0300, Marcelo Tosatti <mtosatti@xxxxxxxxxx> wrote: > On Tue, Jul 03, 2012 at 01:49:49PM +0530, Nikunj A Dadhania wrote: > > On Tue, 3 Jul 2012 04:55:35 -0300, Marcelo Tosatti <mtosatti@xxxxxxxxxx> wrote: > > > > > > > > if (!zero_mask) > > > > goto again; > > > > > > Can you please measure increased vmentry/vmexit overhead? x86/vmexit.c > > > of git://git.kernel.org/pub/scm/virt/kvm/kvm-unit-tests.git should > > > help. > > > > > Sure will get back with the result. > > > > > > + /* > > > > + * Guest might have seen us offline and would have set > > > > + * flush_on_enter. > > > > + */ > > > > + kvm_read_guest_cached(vcpu->kvm, ghc, vs, 2*sizeof(__u32)); > > > > + if (vs->flush_on_enter) > > > > + kvm_x86_ops->tlb_flush(vcpu); > > > > > > > > > So flush_tlb_page which was an invlpg now flushes the entire TLB. Did > > > you take that into account? > > > > > When the vcpu is sleeping/pre-empted out, multiple request for flush_tlb > > could have happened. And now when we are here, it is cleaning up all the > > TLB. > > Yes, cases where there are sufficient exits transforming one TLB entry > invalidation into full TLB invalidation should go unnoticed. > > > One other approach would be to queue the addresses, that brings us with > > the question: how many request to queue? This would require us adding > > more syncronization between guest and host for updating the area where > > these addresses is shared. > > Sounds unnecessarily complicated. > Yes, I did give this a try earlier, but did not see much improvement with the amount of complexity that it was bringing in. Regards Nikunj -- 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
