[vfio-users] VMs slow to a crawl with physical hardware attached

[Curlen M]

Well, I'll be damned. It was the kernel. I rolled over to linux-vfio-lts
and all is well again. Talk about a huge performance regression.

Appreciate all the tips folks

On Tue, Jan 19, 2016 at 6:41 PM Hristo Iliev <hristo at hiliev.eu> wrote:

> On Tue, 19 Jan 2016 16:20:15 +0000 Curlen M <curl2k1 at gmail.com> wrote:
>
> > Current install is Arch with kernel 4.3.3
> >
>
> Hi,
>
> Try using the linux-vfio-lts kernel from AUR. It is based on 4.1.x and
> currently is the only kernel that works for me on my setup (same chipset,
> CPU,
> and amount of memory as yours). Kernel 4.2 and newer have buggy virtual
> MTRR
> implementation that results in VMs booting extremely slowly:
>
> https://bugzilla.kernel.org/show_bug.cgi?id=107561
>
> Check if that is the case by reducing the memory of the VM to 2 GiB - it
> should then boot normally. Kernel 4.4 is supposed to bring the fix.
>
> Regards,
> Hristo
>
> > On Tue, Jan 19, 2016 at 11:11 AM Will Marler <will at wmarler.com> wrote:
> >
> > > What's your host OS/kernel version/etc ?
> > >
> > > On Tue, Jan 19, 2016 at 8:59 AM, Curlen M <curl2k1 at gmail.com> wrote:
> > >
> > >> For the past month, I've been trying to get passthrough to work
> > >> smoothly.  Needless to say, I haven't been successful.  I've tried
> various
> > >> distros, and even rebuilt/upgraded my rig from Z97 to X99 (tbh, I've
> been
> > >> wanting to do that anyway  :-D) thinking things would go smoother.  No
> > >> dice.  Here's what I'm currently using:
> > >>
> > >> ASRock X99 Professional (the Gigabyte and Asus I had before these were
> > >> worse)
> > >> i7 5820k
> > >> 32GB RAM
> > >> Lots-o-drives
> > >> 660Ti
> > >> 680
> > >> Fury X
> > >>
> > >> The setup has both VT-x and VT-d enabled and is booting with the CSM
> > >> disabled.  All 3 GPUs are starting in UEFI GOP mode.
> > >>
> > >>
> > >> The initial plan was to use the 660Ti for the host and assign vfio to
> the
> > >> 680 for a SteamOS instance and the Fury for a W10 instance.  Haven't
> had
> > >> any issues assigning these.  So I'm good here.
> > >>
> > >> I'm able to build the VMs using Virt-Manager and get the OS installed.
> > >> But as soon as I shutdown the VM and assign a video card to either VM
> and
> > >> start it up.  CPU utilization on the host shoots through the roof and
> the
> > >> OS slows to a crawl (noticed this by starting top on accident).  I'm
> > >> talking an hour or more to get to the windows 10 desktop.
> > >>
> > >> I've tried many different configurations (including Seabios and Gerd's
> > >> OVMF).  Including removing the Fury from the system and attempting to
> use
> > >> the 680 in W10 and vice versa.  I've tried ditching Virt-Manager and
> > >> libvirtd and using Qemu start scripts.
> > >>
> > >>
> > >> I've since dropped the 660Ti out of the mix and have been attempting
> to
> > >> use the 680 as the host with the Fury for W10.  Same results.
> > >>
> > >>
> > >> Anyone have any tips?  Ideas?  Anything?
> > >>
> > >> _______________________________________________
> > >> vfio-users mailing list
> > >> vfio-users at redhat.com
> > >> https://www.redhat.com/mailman/listinfo/vfio-users
> > >>
> > >>
> > >
>
>
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