> -----Original Message----- > From: Zhang, Yang Z > Sent: Thursday, November 13, 2014 9:21 AM > To: Wu, Feng; Paolo Bonzini; Alex Williamson > Cc: g...@kernel.org; dw...@infradead.org; j...@8bytes.org; > t...@linutronix.de; mi...@redhat.com; h...@zytor.com; x...@kernel.org; > k...@vger.kernel.org; io...@lists.linux-foundation.org; > linux-kernel@vger.kernel.org > Subject: RE: [PATCH 05/13] KVM: Update IRTE according to guest interrupt > configuration changes > > Wu, Feng wrote on 2014-11-13: > > > > > > kvm-ow...@vger.kernel.org wrote on 2014-11-12: > >> k...@vger.kernel.org; io...@lists.linux-foundation.org; > >> linux-kernel@vger.kernel.org > >> Subject: Re: [PATCH 05/13] KVM: Update IRTE according to guest > >> interrupt configuration changes > >> > >> > >> > >> On 12/11/2014 10:19, Wu, Feng wrote: > >>>> You can certainly backport these patches to distros that do not > >>>> have VFIO. But upstream we should work on VFIO first. VFIO has > >>>> feature parity with legacy device assignment, and adding a new > >>>> feature that is not in VFIO would be a bad idea. > >>>> > >>>> By the way, do you have benchmark results for it? We have not been > >>>> able to see any performance improvement for APICv on e.g. netperf. > >>> > >>> Do you mean benchmark results for APICv itself or VT-d Posted-Interrtups? > >> > >> Especially for VT-d posted interrupts---but it'd be great to know > >> which workloads see the biggest speedup from APICv. > > > > We have some draft performance data internally, please see the > > attached. For VT-d PI, I think we can get the biggest performance gain > > if the VCPU is running in non-root mode for most of the time (not in > > HLT state), since external interrupt from assigned devices will be > > delivered by > guest directly in this case. > > That means we can run some cpu intensive workload in the guests. > > Have you check that the CPU side posted interrupt is taking effect in w/o VT-D > PI case? Per my understanding, the performance gap should be so large if you > use CPU side posted interrupt. This data more like the VT-d PI vs non PI(both > VT-d and CPU).
Yes, this data is VT-d PI vs Non VT-d PI. The CPU side APICv mechanism (including CPU side Posted-Interrtups) is enabled. Thanks, Feng > > > > > Thanks, > > Feng > > > >> > >> Paolo > >> -- > >> To unsubscribe from this list: send the line "unsubscribe kvm" in the > >> body of a message to majord...@vger.kernel.org More majordomo info at > >> http://vger.kernel.org/majordomo-info.html > > > Best regards, > Yang >
