[vfio-users] Looking for performance tips, qemu machine type and pci/pcie-root questionning?

Blank Field ihatethisfield at gmail.com
Fri Apr 15 06:17:43 UTC 2016

On Apr 15, 2016 9:01 AM, "thibaut noah" <thibaut.noah at gmail.com> wrote:
> Speaking of drives, it seems from what i read that it is possible for
qemu/kvm to read a native (non virtualize) install of windows from a
passthrough drive.
> If so is there something special to do? Might go to the hassle of
reinstalling my all windows system by i prefer to be sure before touching
anything (though i might just backup the image, boot my vm from it and
clone windows, much easier than reinstalling).
There is a problem, that i've promised to git bisect, but trashed my fedora
The thing is, you give the whole drive (or just the necessary partitions)
to the vm, and you can either boot the OS inside a VM, or run it bare-metal.
There are some culprits, for example:
If using UEFI, in order to properly mirror the install, you have to copy
the efivars. Windows relies on them to activate itself.
If using not virtio-scsi, you don't send the scsi commands. The most
noteworthy are SMART and TRIM.
And the final one, since some version of OVMF, GPT formatted drive gets
checked for valid MBR and it fails to boot.
But the performance is closest i could get to native, my HDD gets around
150-180MBps, just as it does baremetal.
Not sure about IOPS though.
This kind of setup is useful for AB testing.
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