[vfio-users] Users of X99-boards, can you do me a small favor?

[Brett Peckinpaugh]

What are you settling that fixes the Nvidia experience complaint? 

On October 4, 2016 9:15:56 AM PDT, Hristo Iliev <hristo at hiliev.eu> wrote:
>Hi Martin,
>
>Am 04.10.2016 10:09, schrieb Martin Schrodt:
>> Hi Hristo,
>> 
>>> No need to sleep/wake - my X99-based system starts with TSC
>disabled:
>>> 
>>> $ dmesg | grep TSC
>>> [    0.000000] tsc: Fast TSC calibration using PIT
>>> [    0.077986] TSC deadline timer enabled
>>> [    0.203383] TSC synchronization [CPU#0 -> CPU#1]:
>>> [    0.203384] Measured 974558547804462 cycles TSC warp between
>CPUs,
>>> turning off TSC clock.
>>> [    0.203388] tsc: Marking TSC unstable due to
>check_tsc_sync_source
>>> failed
>>> 
>>> Consequently, tsc is not among the clock sources listed in
>>> available_clocksource. KVM is not happy about that:
>>> 
>>> [16739.200656] kvm: SMP vm created on host with unstable TSC; guest 
>>> TSC
>>> will not be reliable
>> 
>> Ok, so an X99-board that behaves like this even on a fresh start.
>> Interesting.
>> 
>>> But I haven't observed any instabilities of the Windows 10 guest, 
>>> which
>>> happily runs with 4 virtual CPUs (2 virtual hyperthreaded CPUs)
>bound 
>>> to
>>> two cores of my i7-5820K.
>> 
>> This really makes me think there's something else involved in this
>> behaviour. Maybe the CPU configuration (I use "Skylake-Client")
>exposes
>> TSC to the guest, so if you put that on, it'll use it?
>> 
>> Can you check what kind of virtual CPU you use?
>> 
>
>I use 'passthrough', otherwise the default 'Haswell-noTSX' that 
>virt-manager picks results in NVIDIA GeForce Experience complaining 
>about unrecognised CPU type, so the TSC gets pretty much exposed to the
>
>guest.
>
>Just found this paste with a boot log from another system with the same
>
>motherboard, though with an older BIOS version and a Xeon E5-1620 v3 
>CPU:
>
>https://pastelink.net/fjm
>
>It shows the same problem with unsynchronised TSCs. Could also be 
>something specific to the LGA 2011v3 processors or to the EFI BIOS.
>I'll 
>take a look in the BIOS options when time permits.
>
>> Cheers,
>> Martin
>
>Cheers,
>Hristo
>
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