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From: "Wu, Feng" <feng.wu@intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
	"Zhang, Yang Z" <yang.z.zhang@intel.com>,
	"tglx@linutronix.de" <tglx@linutronix.de>,
	"mingo@redhat.com" <mingo@redhat.com>,
	"hpa@zytor.com" <hpa@zytor.com>,
	"x86@kernel.org" <x86@kernel.org>,
	"gleb@kernel.org" <gleb@kernel.org>,
	"dwmw2@infradead.org" <dwmw2@infradead.org>,
	"joro@8bytes.org" <joro@8bytes.org>,
	"alex.williamson@redhat.com" <alex.williamson@redhat.com>,
	"jiang.liu@linux.intel.com" <jiang.liu@linux.intel.com>,
	"Sankaran, Rajesh" <rajesh.sankaran@intel.com>
Cc: "eric.auger@linaro.org" <eric.auger@linaro.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"Wu, Feng" <feng.wu@intel.com>
Subject: RE: [v3 13/26] KVM: Define a new interface kvm_find_dest_vcpu() for VT-d PI
Date: Fri, 19 Dec 2014 01:30:46 +0000	[thread overview]
Message-ID: <E959C4978C3B6342920538CF579893F00230A5F8@SHSMSX104.ccr.corp.intel.com> (raw)
In-Reply-To: <549307A5.3060305@redhat.com>



> -----Original Message-----
> From: Paolo Bonzini [mailto:pbonzini@redhat.com]
> Sent: Friday, December 19, 2014 12:58 AM
> To: Zhang, Yang Z; Wu, Feng; tglx@linutronix.de; mingo@redhat.com;
> hpa@zytor.com; x86@kernel.org; gleb@kernel.org; dwmw2@infradead.org;
> joro@8bytes.org; alex.williamson@redhat.com; jiang.liu@linux.intel.com
> Cc: eric.auger@linaro.org; linux-kernel@vger.kernel.org;
> iommu@lists.linux-foundation.org; kvm@vger.kernel.org
> Subject: Re: [v3 13/26] KVM: Define a new interface kvm_find_dest_vcpu() for
> VT-d PI
> 
> 
> 
> On 18/12/2014 15:49, Zhang, Yang Z wrote:
> >>> Here, we introduce a similar way with 'apic_arb_prio' to handle
> >>> guest lowest priority interrtups when VT-d PI is used. Here is
> >>> the ideas: - Each vCPU has a counter 'round_robin_counter'. -
> >>> When guests sets an interrupts to lowest priority, we choose the
> >>> vCPU with smallest 'round_robin_counter' as the destination, then
> >>> increase it.
> >
> > How this can work well? All subsequent interrupts are delivered to
> > one vCPU? It shouldn't be the best solution, need more consideration.
> 
> Well, it's a hardware limitation.  The alternative (which is easy to
> implement) is to only do PI for single-CPU interrupts.  This should work
> well for multiqueue NICs (and of course for UP guests :)), so perhaps
> it's a good idea to only support that as a first attempt.
> 
> Paolo

Paolo, what do you mean by "single-CPU interrupts"? Do you mean we don't
support lowest priority interrupts for PI? But Linux OS uses lowest priority
for most of the case? If so, we can hardly get benefit from this feature for
Linux guest OS.

Thanks,
Feng

> 
> > Also, I think you should take the apic_arb_prio into consider since
> > the priority is for the whole vCPU not for one interrupt.

  parent reply	other threads:[~2014-12-19  1:30 UTC|newest]

Thread overview: 141+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-12-12 15:14 [v3 00/26] Add VT-d Posted-Interrupts support Feng Wu
2014-12-12 15:14 ` [v3 01/26] genirq: Introduce irq_set_vcpu_affinity() to target an interrupt to a VCPU Feng Wu
2014-12-12 15:14 ` [v3 02/26] iommu: Add new member capability to struct irq_remap_ops Feng Wu
2015-01-28 15:22   ` David Woodhouse
2015-01-29  8:34     ` Wu, Feng
2014-12-12 15:14 ` [v3 03/26] iommu, x86: Define new irte structure for VT-d Posted-Interrupts Feng Wu
2015-01-28 15:26   ` David Woodhouse
2014-12-12 15:14 ` [v3 04/26] iommu, x86: Implement irq_set_vcpu_affinity for intel_ir_chip Feng Wu
2015-01-28 15:26   ` David Woodhouse
2015-01-29  7:55     ` Wu, Feng
2014-12-12 15:14 ` [v3 05/26] x86, irq: Implement irq_set_vcpu_affinity for pci_msi_ir_controller Feng Wu
2014-12-12 15:14 ` [v3 06/26] iommu, x86: No need to migrating irq for VT-d Posted-Interrupts Feng Wu
2014-12-18 14:26   ` Zhang, Yang Z
2014-12-19  1:40     ` Wu, Feng
2014-12-19  1:46       ` Zhang, Yang Z
2014-12-19 11:59         ` Paolo Bonzini
2014-12-23  0:37           ` Zhang, Yang Z
2014-12-23  8:47             ` Paolo Bonzini
2014-12-23  9:07               ` Wu, Feng
2014-12-23  9:34                 ` Paolo Bonzini
2014-12-24  1:38                   ` Zhang, Yang Z
2014-12-24  2:12                     ` Jiang Liu
2014-12-24  2:32                       ` Zhang, Yang Z
2014-12-24  3:08                         ` Wu, Feng
2014-12-24  4:04                           ` Zhang, Yang Z
2014-12-24  4:54                         ` Jiang Liu
2015-01-28 15:29   ` David Woodhouse
2014-12-12 15:14 ` [v3 07/26] iommu, x86: Add cap_pi_support() to detect VT-d PI capability Feng Wu
2015-01-28 15:32   ` David Woodhouse
2014-12-12 15:14 ` [v3 08/26] iommu, x86: Add intel_irq_remapping_capability() for Intel Feng Wu
2015-01-28 15:37   ` David Woodhouse
2015-01-29  8:57     ` Wu, Feng
2014-12-12 15:14 ` [v3 09/26] iommu, x86: define irq_remapping_cap() Feng Wu
2014-12-12 15:14 ` [v3 10/26] KVM: change struct pi_desc for VT-d Posted-Interrupts Feng Wu
2014-12-12 15:14 ` [v3 11/26] KVM: Add some helper functions for Posted-Interrupts Feng Wu
2014-12-12 15:14 ` [v3 12/26] KVM: Initialize VT-d Posted-Interrupts Descriptor Feng Wu
2014-12-18 15:19   ` Zhang, Yang Z
2014-12-12 15:14 ` [v3 13/26] KVM: Define a new interface kvm_find_dest_vcpu() for VT-d PI Feng Wu
2014-12-18 14:49   ` Zhang, Yang Z
2014-12-18 16:58     ` Paolo Bonzini
2014-12-19  1:13       ` Zhang, Yang Z
2014-12-19  1:30         ` Wu, Feng
2014-12-19  1:30       ` Wu, Feng [this message]
2014-12-19  1:47         ` Zhang, Yang Z
2014-12-19 11:59         ` Paolo Bonzini
2014-12-19 23:48           ` Wu, Feng
2014-12-20 13:16             ` Paolo Bonzini
2014-12-22  4:48               ` Wu, Feng
2014-12-22  9:27                 ` Paolo Bonzini
2014-12-22 11:04                   ` Wu, Feng
2014-12-22 11:06                     ` Paolo Bonzini
2014-12-22 11:17                       ` Wu, Feng
2014-12-22 11:23                         ` Paolo Bonzini
2014-12-22 14:13                           ` Yong Wang
2015-01-09 14:54   ` Radim Krčmář
2015-01-09 14:56     ` Paolo Bonzini
2015-01-09 15:12       ` Radim Krčmář
2015-01-09 15:18         ` Paolo Bonzini
2015-01-09 15:47           ` Radim Krčmář
2015-01-13  0:27       ` Wu, Feng
2015-01-13 16:17         ` Radim Kr?má?
2015-01-14  1:27           ` Wu, Feng
2015-01-14 13:02             ` Paolo Bonzini
2015-01-14 16:59             ` Radim Kr?má?
2015-01-20 21:04               ` Nadav Amit
2015-01-21 21:16                 ` Radim Kr?má?
2014-12-12 15:14 ` [v3 14/26] KVM: Get Posted-Interrupts descriptor address from struct kvm_vcpu Feng Wu
2014-12-12 15:14 ` [v3 15/26] KVM: add interfaces to control PI outside vmx Feng Wu
2014-12-12 15:14 ` [v3 16/26] KVM: Make struct kvm_irq_routing_table accessible Feng Wu
2014-12-17 16:17   ` Paolo Bonzini
2014-12-19  2:19     ` Wu, Feng
2014-12-19 11:59       ` Paolo Bonzini
2014-12-19 23:39         ` Wu, Feng
2014-12-12 15:14 ` [v3 17/26] KVM: make kvm_set_msi_irq() public Feng Wu
2014-12-17 17:32   ` Paolo Bonzini
2014-12-12 15:14 ` [v3 18/26] KVM: kvm-vfio: User API for VT-d Posted-Interrupts Feng Wu
2014-12-12 15:14 ` [v3 19/26] KVM: kvm-vfio: implement the VFIO skeleton " Feng Wu
2014-12-12 15:14 ` [v3 20/26] KVM: x86: kvm-vfio: VT-d posted-interrupts setup Feng Wu
2014-12-12 15:14 ` [v3 21/26] x86, irq: Define a global vector for VT-d Posted-Interrupts Feng Wu
2014-12-18 14:54   ` Zhang, Yang Z
2014-12-19  0:52     ` Wu, Feng
2015-01-30 18:18   ` H. Peter Anvin
2015-02-02  1:06     ` Wu, Feng
2015-02-23 22:04   ` Marcelo Tosatti
2014-12-12 15:14 ` [v3 22/26] KVM: Define a wakeup worker thread for vCPU Feng Wu
2014-12-12 15:14 ` [v3 23/26] KVM: Update Posted-Interrupts Descriptor when vCPU is preempted Feng Wu
2014-12-17 17:11   ` Paolo Bonzini
2014-12-18  3:15     ` Wu, Feng
2014-12-18  8:32       ` Paolo Bonzini
2014-12-19  2:09         ` Wu, Feng
2015-02-23 22:21   ` Marcelo Tosatti
2015-03-02  9:12     ` Wu, Feng
2014-12-12 15:14 ` [v3 24/26] KVM: Update Posted-Interrupts Descriptor when vCPU is blocked Feng Wu
2014-12-17 17:09   ` Paolo Bonzini
2014-12-18  3:16     ` Wu, Feng
2014-12-18  8:37       ` Paolo Bonzini
2014-12-19  2:51         ` Wu, Feng
2015-02-25 21:50   ` Marcelo Tosatti
2015-02-26  8:08     ` Wu, Feng
2015-02-26 23:41       ` Marcelo Tosatti
2015-02-26 23:40   ` Marcelo Tosatti
2015-03-02 13:36     ` Wu, Feng
2015-03-04 12:06       ` Marcelo Tosatti
2015-03-06  6:51         ` Wu, Feng
2015-03-12  1:15           ` Marcelo Tosatti
2015-03-16 11:42             ` Wu, Feng
2015-03-25 23:17               ` Marcelo Tosatti
2015-03-27  6:34                 ` Wu, Feng
2015-03-27 19:30                   ` Marcelo Tosatti
2015-03-30  4:46                     ` Wu, Feng
2015-03-30 23:55                       ` Marcelo Tosatti
2015-03-31  1:13                         ` Wu, Feng
2015-04-14  7:37                         ` Wu, Feng
2015-06-05 21:59                           ` Marcelo Tosatti
2015-06-08  1:43                             ` Wu, Feng
2014-12-12 15:14 ` [v3 25/26] KVM: Suppress posted-interrupt when 'SN' is set Feng Wu
2014-12-17 17:42   ` Paolo Bonzini
2014-12-18  3:14     ` Wu, Feng
2014-12-18  8:38       ` Paolo Bonzini
2014-12-18 15:09         ` Zhang, Yang Z
2014-12-19  2:58           ` Wu, Feng
2014-12-19  3:32             ` Zhang, Yang Z
2014-12-19  4:34               ` Wu, Feng
2014-12-19  4:44                 ` Zhang, Yang Z
2014-12-19  4:49                   ` Wu, Feng
2014-12-19  5:25                     ` Zhang, Yang Z
2014-12-19  5:46                       ` Wu, Feng
2014-12-19  7:04                         ` Zhang, Yang Z
2014-12-19 12:00                       ` Paolo Bonzini
2014-12-19 23:34                         ` Wu, Feng
2014-12-12 15:15 ` [v3 26/26] iommu/vt-d: Add a command line parameter for VT-d posted-interrupts Feng Wu
2015-01-28 15:39   ` David Woodhouse
2014-12-16  9:04 ` [v3 00/26] Add VT-d Posted-Interrupts support Wu, Feng
2015-01-06  1:10 ` Wu, Feng
2015-01-09 12:46   ` joro
2015-01-09 13:58     ` Wu, Feng
2015-01-21  2:25 ` Wu, Feng
2015-01-28  3:01   ` Wu, Feng
2015-01-28  3:44     ` Alex Williamson
2015-01-28  4:44       ` Wu, Feng
     [not found] <1415059685.1337085.1419266271242.JavaMail.zimbra@zmail13.collab.prod.int.phx2.redhat.com>
2014-12-23  0:46 ` [v3 13/26] KVM: Define a new interface kvm_find_dest_vcpu() for VT-d PI Zhang, Yang Z

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