Re: Extremely slow network with e1000 & ip_conntrack

David S. Miller
2003-12-04T18:25:44Z

On Thu, 04 Dec 2003 21:36:09 +0900
Stephen Lee <mukansai@emailplus.org> wrote:

> "Feldman, Scott" <scott.feldman@intel.com> wrote:
> >
> > Try turning off TSO by disabling this code or by using "ethtool -K tso
> > off" (need version 1.8).
>
> Yes, turning off TSO with ethtool fixed it (tested on 2.6.0-test11). At
> least we have a workaround now.
>
> Thanks Scott, Harald and Dave.
>
> Is it not supported by the hardware? Seems TSO could improve
> performance a bit since the 1000/MT Desktop is starved for PCI bandwidth
> at 32-bit/33MHz.

This workaround explains everything. The TSO packets have to be
"un-TSO'd" in order for netfilter to look at the packet and parse
the contents. This means copying all the data around, allocating
several networking buffers, etc.