em interface slow down on 8.0R

[Pyun YongHyeon]

On Mon, Jan 25, 2010 at 08:25:43AM -0800, Nick Rogers wrote:
> I have not tried toying with any tcp sysctl. I'm not having performance
> problems so much as the interface just stops working entirely, which I would
> think has nothing to do with the TCP stack when layer 2 is not functioning?
> 

I'm not sure you're seeing a checksum offload bug of em(4) but the
bug is easily reproducible in VLAN environments. If the issue is
gone when you disable TX checksum offloading, see kern/141843 for
for more detailed information as well as fix.

> I'll give it a shot if I can. For the moment I have had to switch to a
> different (lower performance) network card to get things stable and I would
> like to be aware of a more concrete driver fix in STABLE before switching
> back my production machines.
> 
> On Mon, Jan 25, 2010 at 6:25 AM, Lars Eggert <lars.eggert at nokia.com> wrote:
> 
> > Hi,
> >
> > have you tried turning off TCP Segmentation Offloading (net.inet.tcp.tso
> > sysctl)? That fixed performance issues with some em cards for me.
> >
> > Lars
> >
> >