Re: [Qemu-devel] [Bug 1036363] Re: Major network performance problems on AMD hardware

[Stefan Hajnoczi]

On Sun, Aug 26, 2012 at 1:08 AM, Ziemowit Pierzycki
<address@hidden> wrote:
> Executed another test:
>
> F16 KVM <-- 15 gbps --> F17 VM
>
> So why is F16 much faster?

You could try "bisecting" to find the change that slowed down networking:

$ git clone git://git.kernel.org/pub/scm/virt/kvm/qemu-kvm.git
$ cd qemu-kvm

# Test qemu-kvm 0.15.0, which F16 qemu-kvm is based on
$ git checkout qemu-kvm-0.15.0
$ ./configure && make
$ ...run test...

# Test qemu-kvm 1.0, which F17 qemu-kvm is based on
$ git checkout qemu-kvm-1.0
$ ./configure && make
$ ...run test...

If the 0.15.0 vs 1.0 results show the same change as F16 vs F17, then
you can use git-bisect(1):

$ git bisect start qemu-kvm-1.0 qemu-kvm-0.15.0

http://www.kernel.org/pub/software/scm/git/docs/git-bisect.html
http://git-scm.com/book/en/Git-Tools-Debugging-with-Git#Binary-Search

The bisect will leave you at a commit where the performance regression
was introduced.

Stefan