Re: [PATCH 00/10] KVM: x86/pmu: Optimize triggering of emulated events

Konstantin Khorenko
2023-11-16T16:37:17Z

On 10.11.2023 15:56, Sean Christopherson wrote:
> On Thu, Nov 09, 2023, Dongli Zhang wrote:
>> Hi Sean,
>>
>> On 11/9/23 18:28, Sean Christopherson wrote:
>>> base-commit: ef1883475d4a24d8eaebb84175ed46206a688103
>> May I have a silly question?
>>
>> May I have the tree that the commit is the base? I do not find it in kvm-x86.
>>
>> https://github.com/kvm-x86/linux/commit/ef1883475d4a24d8eaebb84175ed46206a688103
> It's kvm-x86/next (which I failed to explicitly call out), plus two PMU series
> as mentioned in the cover letter.
>
> https://lore.kernel.org/all/20231103230541.352265-1-seanjc@google.com
> https://lore.kernel.org/all/20231110021306.1269082-1-seanjc@google.com

Hi Sean,

i have tested my testcase on your patchset, results look impressive, thank you for your work!
Note, for AMD node PMU totally disabled case gave a bit worse results on kvm-next kernel vs stock
latest mainstream.

The difference is tiny though.

*AMD node*: CPU: AMD Zen 3 (three!): AMD EPYC 7443P 24-Core Processor
-----------------------------------------------------------------------------------------
| Kernel | CPUID rate |
-----------------------------------------------------------------------------------------
| stock ms 6.6.0+ (commit 305230142ae0) | 1360250 |
| stock ms 6.6.0+ + kvm.enable_pmu=0 | 1542894 (+13.4%) |
| kvm-next ms 6.6.0+ + patches from Sean + kvm.enable_pmu=1 | 1498864 |
| kvm-next ms 6.6.0+ + patches from Sean + kvm.enable_pmu=0 | 1526396 (+1.84%) |
-----------------------------------------------------------------------------------------

*Intel node*: CPU: Intel(R) Xeon(R) E-2136 CPU @ 3.30GHz
-----------------------------------------------------------------------------------------
| Kernel | CPUID rate |
-----------------------------------------------------------------------------------------
| stock ms 6.6.0+ | 1431608 |
| stock ms 6.6.0+ + kvm.enable_pmu=0 | 1553839 (+8.5%) |
| kvm-next ms 6.6.0+ + patches from Sean + kvm.enable_pmu=1 | 1559365 |
| kvm-next ms 6.6.0+ + patches from Sean + kvm.enable_pmu=0 | 1582281 (+1.5%) |
-----------------------------------------------------------------------------------------

Note: in order to disable PMU completely i used "kvm" module "enable_pmu=0" option
(not used KVM_PMU_CAP_DISABLEthis time).

Hope that helps.

--
Best regards,

Konstantin Khorenko,
Virtuozzo Linux Kernel Team