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

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Date:   Thu, 16 Nov 2023 17:37:11 +0100
From:   Konstantin Khorenko <khorenko@...tuozzo.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Dongli Zhang <dongli.zhang@...cle.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jim Mattson <jmattson@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: Re: [PATCH 00/10] KVM: x86/pmu: Optimize triggering of emulated
 events

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