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Date:   Tue, 31 May 2022 17:51:47 +0200
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To:     "Durrant, Paul" <pdurrant@amazon.co.uk>,
        Peter Zijlstra <peterz@infradead.org>,
        "Allister, Jack" <jalliste@amazon.com>
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From:   Paolo Bonzini <pbonzini@redhat.com>
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On 5/31/22 16:52, Durrant, Paul wrote:
>> -----Original Message-----
>> From: Peter Zijlstra <peterz@infradead.org>
>> Sent: 31 May 2022 15:44
>> To: Allister, Jack <jalliste@amazon.com>
>> Cc: bp@alien8.de; diapop@amazon.co.uk; hpa@zytor.com; jmattson@google.com; joro@8bytes.org;
>> kvm@vger.kernel.org; linux-kernel@vger.kernel.org; metikaya@amazon.co.uk; mingo@redhat.com;
>> pbonzini@redhat.com; rkrcmar@redhat.com; sean.j.christopherson@intel.com; tglx@linutronix.de;
>> vkuznets@redhat.com; wanpengli@tencent.com; x86@kernel.org
>> Subject: RE: [EXTERNAL]...\n
>>
>>
>> On Tue, May 31, 2022 at 02:02:36PM +0000, Jack Allister wrote:
>>> The reasoning behind this is that you may want to run a guest at a
>>> lower CPU frequency for the purposes of trying to match performance
>>> parity between a host of an older CPU type to a newer faster one.
>>
>> That's quite ludicrus. Also, then it should be the host enforcing the
>> cpufreq, not the guest.
> 
> I'll bite... What's ludicrous about wanting to run a guest at a lower CPU freq to minimize observable change in whatever workload it is running?

Well, the right API is cpufreq, there's no need to make it a KVM 
functionality.

Paolo