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List:       libvirt-users
Subject:    [libvirt-users] KVM guest incorrect CPU frequency
From:       xmbbb <xmbbb () protonmail ! com>
Date:       2017-11-13 21:13:59
Message-ID: OhA2J911sxQyhf6Rx4_xjcR4f0XucC-px7JdIKgHqNi8AXEkSzZ0ubrwl0B77JARMv_XqtDKtBCk6sYRH6wRK8plFoHln_CiIpBqP3iXQlk= () protonmail ! com
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Hello,

I am facing an issue where the detected CPU frequencies in KVM guests are incorrect.

I am using the new Core i9 7900x with base clock 3.3GHz with "host-passthrough". Both \
Win10 and Linux guests incorrectly detect 3.45GHz for some reason.

The workaround I have found is to temporarily switch to use HPET clocksource in the \
HOST before starting the VM. This makes the VMs correctly detect a 3.3GHz CPU. Then I \
can safely switch back to TSC in the VM HOST.

This mostly does not impact much for day to day use. The only reproducible bug I can \
find with an incorrect CPU frequency is playing Bink videos that come with PC games. \
If I play any Bink video cut scene from the 2013 Tomb Raider game with the incorrect \
CPU frequency, the video plays a little slower than intended which results in audio \
cut out once in a while so that the video can "catch up" to the audio.

Anyone having experiences with similar issues?


[Attachment #3 (text/html)]

<div>Hello,<br></div><div><br></div><div>I am facing an issue where the detected CPU \
frequencies in KVM guests are incorrect. <br></div><div><br></div><div>I am using the \
new Core i9 7900x with base clock 3.3GHz with "host-passthrough". Both Win10 and \
Linux guests incorrectly detect 3.45GHz for some \
reason.<br></div><div><br></div><div>The workaround I have found is to temporarily \
switch to use HPET clocksource in the HOST before starting the VM. This makes the VMs \
correctly detect a 3.3GHz CPU. Then I can safely switch back to TSC in the VM \
HOST.<br></div><div><br></div><div>This mostly does not impact much for day to day \
use. The only reproducible bug I can find with an incorrect CPU frequency is playing \
Bink videos that come with PC games. If I play any Bink video cut scene from the 2013 \
Tomb Raider game with the incorrect CPU frequency, the video plays a little  slower \
than intended which results in audio cut out once in a while so that the video can \
"catch up" to the audio.<br></div><div><br></div><div>Anyone having experiences with \
similar issues?</div>



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