em interface slow down on 8.0R

[Nick Rogers]

On Mon, Jan 25, 2010 at 10:22 AM, Pyun YongHyeon <pyunyh at gmail.com> wrote:

> 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.
>

Good to know, but I am having a similar problem on another em(4) interface
that has no VLAN interfaces.

>
> > 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
> > >
> > >
>