linux-kernel - RE: [PATCH 05/13] KVM: Update IRTE according to guest interrupt configuration changes

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 13 Nov 2014 01:21:16 +0000
From:	"Zhang, Yang Z" <yang.z.zhang@...el.com>
To:	"Wu, Feng" <feng.wu@...el.com>,
	Paolo Bonzini <pbonzini@...hat.com>,
	"Alex Williamson" <alex.williamson@...hat.com>
CC:	"gleb@...nel.org" <gleb@...nel.org>,
	"dwmw2@...radead.org" <dwmw2@...radead.org>,
	"joro@...tes.org" <joro@...tes.org>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"hpa@...or.com" <hpa@...or.com>, "x86@...nel.org" <x86@...nel.org>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 05/13] KVM: Update IRTE according to guest interrupt
 configuration changes

Wu, Feng wrote on 2014-11-13:
> 
> 
> kvm-owner@...r.kernel.org wrote on 2014-11-12:
>> kvm@...r.kernel.org; iommu@...ts.linux-foundation.org; 
>> linux-kernel@...r.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).

> 
> Thanks,
> Feng
> 
>> 
>> Paolo
>> --
>> To unsubscribe from this list: send the line "unsubscribe kvm" in the 
>> body of a message to majordomo@...r.kernel.org More majordomo info at 
>> http://vger.kernel.org/majordomo-info.html


Best regards,
Yang