em interface slow down on 8.0R

[Jeremy Chadwick]

On Tue, Jan 26, 2010 at 11:09:45PM -0800, Nick Rogers wrote:
> Can anyone clarify if I should be looking to disable TSO or TXCSUM, or both,
> or does disabling either one somehow work around the problem? Thanks a lot.
> 
> On Mon, Jan 25, 2010 at 8:31 PM, Joshua Boyd <boydjd at jbip.net> wrote:
> 
> > I've been having a similar problem with my network dropping completely on
> > my
> > 8-STABLE gateway/firewall/fileserver. My setup is a little different, as I
> > have re0 and ral0 bridged for LAN, and em0 for WAN. I've just turned off TX
> > checksum offloading to see if that makes any difference.
> >
> > On Mon, Jan 25, 2010 at 1:49 PM, Lars Eggert <lars.eggert at nokia.com>
> > wrote:
> >
> > > Hi,
> > >
> > > On 2010-1-25, at 19:38, Nick Rogers wrote:
> > > >> On Mon, Jan 25, 2010 at 10:22 AM, Pyun YongHyeon <pyunyh at gmail.com>
> > > wrote:
> > > >> 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.
> > >
> > > FYI, I also have these issues without using VLANs, and turning off TSO
> > > fixed them.

The recommendation is to disable TSO (TCP Segmentation Offloading) as
well as TXCSUM (TCP Checksum Offloading).

-- 
| Jeremy Chadwick                                   jdc at parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.              PGP: 4BD6C0CB |