[libvirt] Analysis of the effect of adding PCIe root ports

[Richard W.M. Jones]

On Thu, Oct 06, 2016 at 10:00:39AM -0400, Laine Stump wrote:
> * <controller type='usb' model='blah'> x 4 - a set of USB2
> controllers. This will turn into a single USB3 controller on a
> root-port after my patches. Alternately, since it seems you don't
> use it, you could eliminate it with:

Yup, this is auto-added, and a mistake.

I have sent a patch upstream adding:

>      <controller type='usb' model='none'/>
>     <memballoon model='none'/>

...
> 1) virtio-scsi controller
> 2) virtio-serial controller
> 
> and nothing else. Manually address those two to be on bus 0
> (pcie-root), and (with my patches) you've reduced your PCI
> device+controller count from the current 10 down to 3 (including the
> sata controller).

Interesting.  Is there any particular reason why we should or should
not use explicit PCI addresses for the remaining devices?  What would
you recommend we do?

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
virt-builder quickly builds VMs from scratch
http://libguestfs.org/virt-builder.1.html