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

thibaut noah thibaut.noah at gmail.com
Tue Apr 19 21:01:52 UTC 2016

So, i switch my vm container to bare metal in order to do some bench with
native windows install.
Seems the difference between vm and native in 3dmark firestrike is about
3%, just so you know.

2016-04-15 8:17 GMT+02:00 Blank Field <ihatethisfield at gmail.com>:

> 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 instead.
> 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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