Wu, Feng wrote on 2014-11-13: > > > Zhang, Yang Z wrote on 2014-11-13: >> k...@vger.kernel.org; iommu@lists.linux-foundation.org; >> linux-ker...@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; iommu@lists.linux-foundation.org; >>>> linux-ker...@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.
>From the CPU utilization data, it seems the environment of APICv is not >reasonable to me. with current APICv, the interrupt should not deliver to the >PCPU where vcpu is running. Otherwise, it will force the vcpu vmexit and the >CPU side posted interrupt cannot take effect. Do you set the interrupt >affinity manually? > > 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 >> Best regards, Yang _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
