[fedora-virt] Poor performace for e1000 and other fully virtualized netcard

[Ján ONDREJ (SAL)]

Hello,

  today I disovered, that e1000 cards has very poor performance in Fedora 18
and 19. Does not matter, if guest is an Linux or other system.
By "poor" I mean TCP network transfers about 5-90 kB/s, even if they are on
an gigabit network.

  By downgrading kernel on Fedora 19 from 3.10.X to
kernel-3.9.5-301.fc19.x86_64 fixed my problem, so looks like there
is an bug in kernel. I tested these kernels:

Fast:
	kernel-3.9.5-301.fc19.x86_64

Slow:
	kernel-3.10.7-100.fc18.x86_64
	kernel-3.10.9-100.fc18.x86_64
	kernel-3.10.10-200.fc19.x86_64

Looks like it is an change with kernel-3.10.X. I can test other kernels if
requested.

For me, it's easy to reproduce. Tested on 4 host machines, 2 Fedoras,
multiple kernels and different guests. Also tested some network cards,
e1000, pcnet, ... All with similar problems.

As described in other bug, virtio net driver has time skew problems, so
I can't use it. :-(

Any ideas, how to solve this problem?

			Regards

						SAL