[vfio-users] Calling ALL VM experts - Seeking assistance with AMD FX CPUs

[Zachary Boley]

It seems everything is alright, I would try hugepages and see if that helps
it describes how to do it in the arch wikis guide on pci passthrough

On Jan 30, 2017 10:48 PM, "Alyx" <overlordalyx at gmail.com> wrote:

> Hopefully this reply works.
> So. I have an FX-8350. I have the exact issue as described, and believe
> the person he was talking about.
>
> Here's my config - http://pastebin.com/McuiqyDt
> Note that the above config is just the one I am running just now and has
> some options that have no effect, such as "vmport=off", in a desperation
> attempt to see if any option makes a difference.
>
> So I've tried many things to get the stuttering to subside. I've tried,
> changing the kernel tick-rate, changing to a realtime kernel, changing to
> the CK kernel (with the belief that a different I/O scheduler might solve
> it), making the VM BIOS, changing the pre-emptive state of the kernel,
> changing the PCIE slot of the GPU (so that it is now in slot 1, and the
> "main" GPU in slot 2), isolating cores, hugepages, moving threads via cset.
> And of course a combination of all of the above. The only thing that sort
> of solves it if I reduce the number of cores I pass to the VM, more than 4
> and it increases the stuttering, and less than 4 makes it not really
> powerful enough for higher-end gaming.
>
> There was a random thought that it could've been something to do with the
> shared FPU, however after isolating the last 6 cores and only passing every
> second core (3, 5, 7) so that they are on separate FPU modules (meaning
> that it's "pair" is not doing any work at all), yields the same results as
> passing 3 cores normally.
>
> I would describe the issue as a stuttering of sorts, where the game
> freezes and then suddenly speeds up to catch back up to realtime (sound
> usually works as normal during the stutter as if nothing happened). It's
> fine within a desktop environment and when doing benchmarks such as
> Cinebench and Unigine-Heaven (Heaven being exactly the same as bare metal).
> However it's when I move into a more game-like situation such as 3D Mark's
> benchmarks where the stuttering appears. Some 3D Mark benchmarks can even
> cause the VM/Program to freeze such as the API overhead test which also
> displays a large amount of stuttering during the test (assuming it doesn't
> crash half way though of course). Another program-specific issue is that
> the program HWINFO also locks up the entire VM when it tries to detect the
> CPU (works on Intel hardware) causing Windows to shut down after a ~10
> seconds. Sure the HWINFO isn't too much of an issue, but it could be
> related.
> The stuttering becomes more apparent as the game tries to load in
> textures, for example exiting out of a safe area into a large open world
> (Game: The Division) causes huge amounts of stuttering until everything has
> finished "popping-in". However, once everything has loaded in, if I look at
> the frametimes in MSI Afterburner I can see that it varies dramatically, so
> I'll be at 60 FPS and see the frametimes jump from low ~20ms to 100ms+ with
> no "big" stuttering like when the textures are loading.
>
> Any help is appreciated and I'll try any suggestions at this point
>
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