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Re: [Qemu-devel] [PATCH V7 0/2] Add option to configure guest vPMU
From: |
Andrew Jones |
Subject: |
Re: [Qemu-devel] [PATCH V7 0/2] Add option to configure guest vPMU |
Date: |
Mon, 24 Oct 2016 10:49:20 +0200 |
User-agent: |
Mutt/1.6.0.1 (2016-04-01) |
On Fri, Oct 21, 2016 at 05:53:00PM -0400, Wei Huang wrote:
> This patchset adds a pmu=[on/off] option to enable/disable vPMU support
> for guest VM. There are several reasons to justify this option. First,
> vPMU can be problematic for cross-migration between different SoC as perf
> counters are architecture-dependent. It is more flexible to have an option
> to turn it on/off. Secondly this option matches the "pmu" option as
> supported in libvirt. To make sure backward compatible, a PMU-related
> property is added to mach-virt machine types.
>
> The following are testing results with this patchset:
> CONFIG (qemu-system-aarch64) vPMU WARNING
> -M virt-2.8/virt,accel=kvm -cpu host YES NO
> -M virt-2.8/virt,accel=kvm -cpu host,pmu=off NO NO
> -M virt-2.8/virt,accel=kvm -cpu host,pmu=on YES NO
> -M virt-2.7,accel=kvm -cpu host YES NO
> -M virt-2.7,accel=kvm -cpu host,pmu=off NO NO
> -M virt-2.7,accel=kvm -cpu host,pmu=on YES NO
> -M virt-2.6,accel=kvm -cpu host NO NO
> -M virt-2.6,accel=kvm -cpu host,pmu=off NO NO
> -M virt-2.6,accel=kvm -cpu host,pmu=on NO NO
>
> -M virt-2.8/virt,accel=tcg -cpu cortex-a57 NO NO
> -M virt-2.8/virt,accel=tcg -cpu cortex-a57,pmu=off NO "No PMU property"
> -M virt-2.8/virt,accel=tcg -cpu cortex-a57,pmu=on NO "No PMU property"
> -M virt-2.7,accel=tcg -cpu cortex-a57 NO NO
> -M virt-2.7,accel=tcg -cpu cortex-a57,pmu=off NO "No PMU property"
> -M virt-2.7,accel=tcg -cpu cortex-a57,pmu=on NO "No PMU property"
> -M virt-2.6,accel=tcg -cpu cortex-a57 NO NO
> -M virt-2.6,accel=tcg -cpu cortex-a57,pmu=off NO "No PMU property"
> -M virt-2.6,accel=tcg -cpu cortex-a57,pmu=on NO "No PMU property"
>
> -M virt-2.8/virt,accel=tcg -cpu cortex-a15 NO NO
> -M virt-2.8/virt,accel=tcg -cpu cortex-a15,pmu=off NO "No PMU property"
> -M virt-2.8/virt,accel=tcg -cpu cortex-a15,pmu=on NO "No PMU property"
> -M virt-2.7,accel=tcg -cpu cortex-a15 NO NO
> -M virt-2.7,accel=tcg -cpu cortex-a15,pmu=off NO "No PMU property"
> -M virt-2.7,accel=tcg -cpu cortex-a15,pmu=on NO "No PMU property"
> -M virt-2.6,accel=tcg -cpu cortex-a15 NO NO
> -M virt-2.6,accel=tcg -cpu cortex-a15,pmu=off NO "No PMU property"
> -M virt-2.6,accel=tcg -cpu cortex-a15,pmu=on NO "No PMU property"
>
> * "No PMU property" msg, e.g.
> can't apply global cortex-a15-arm-cpu.pmu=off: Property '.pmu' not found
>
> V6->V7:
> * change has_pmu variable type from OnOffAuto to Boolean
> * only add "pmu" property to CPU under kvm mode, default ON
Hmm, if we don't allow the property with TCG then switching a guest from
KVM to TCG will require more than just an accelerator switch. That's a
bit annoying and I think we'd have to teach it to libvirt too. I'd prefer
-M virt-2.8,accel=tcg -cpu cortex-a57 NO NO
-M virt-2.8,accel=tcg -cpu cortex-a57,pmu=off NO NO
-M virt-2.8,accel=tcg -cpu cortex-a57,pmu=on NO "Warning: PMU not
yet supported with TCG" (or something)
> * set no_pmu=true for machvirt-2.6
>
> V5->V6:
> * adapt patches for new machine type 2.8
>
> V4->V5:
> * remove comment change for has_pmu
> * remove warning msg when pmu_default_on=TRUE && has_pmu=AUTO && tcg=TRUE
>
> V3->V4:
> * change has_pmu from Boolean to OnOffAuto to handle different cases
> * "pmu" property is re-defined as DEFINE_PROP_ON_OFF_AUTO
>
> V2->V3:
> * revise patch 1 commit msg and if-else statement (Drew)
> * move property field into VirtMachineClass (Drew)
>
> V1->V2:
> * keep the original field name as "has_pmu"
> * add a warning message when PMU is turned on without KVM
> * use the feature bit to check PMU availability, instead of using has_pmu
> * add PMU compat support to mach-virt machine type
>
> RFC->V1:
> * set default pmu=off
> * change struct ARMCPU field name "has_pmu" ==> "has_host_pmu"
> * like el3, add a new feature ARM_FEATURE_HOST_PMU
> * "pmu" property becomes CPU dependent. Only cortex-a53/cortex-a57/host
> running on kvm supports this option.
>
> Thanks,
> -Wei
>
> Wei Huang (2):
> arm64: Add an option to turn on/off vPMU support
> arm: virt: add PMU property to mach-virt machine type
>
> hw/arm/virt-acpi-build.c | 2 +-
> hw/arm/virt.c | 9 ++++++++-
> target-arm/cpu.c | 14 ++++++++++++++
> target-arm/cpu.h | 1 +
> target-arm/cpu64.c | 2 ++
> target-arm/kvm64.c | 17 ++++++++++++++---
> 6 files changed, 40 insertions(+), 5 deletions(-)
>
> --
> 1.8.3.1
>
>
- [Qemu-devel] [PATCH V7 0/2] Add option to configure guest vPMU, Wei Huang, 2016/10/21
- [Qemu-devel] [PATCH V7 2/2] arm: virt: add PMU property to mach-virt machine type, Wei Huang, 2016/10/21
- [Qemu-devel] [PATCH V7 1/2] arm: Add an option to turn on/off vPMU support, Wei Huang, 2016/10/21
- Re: [Qemu-devel] [PATCH V7 0/2] Add option to configure guest vPMU,
Andrew Jones <=
- Re: [Qemu-devel] [PATCH V7 0/2] Add option to configure guest vPMU, Wei Huang, 2016/10/25
- Re: [Qemu-devel] [PATCH V7 0/2] Add option to configure guest vPMU, Wei Huang, 2016/10/25
- Re: [Qemu-devel] [PATCH V7 0/2] Add option to configure guest vPMU, Andrew Jones, 2016/10/25
- Re: [Qemu-devel] [PATCH V7 0/2] Add option to configure guest vPMU, Wei Huang, 2016/10/25
- Re: [Qemu-devel] [PATCH V7 0/2] Add option to configure guest vPMU, Andrew Jones, 2016/10/26