r8169: slow samba performance

Just upgraded a motherboard and it came with an onboard
Realtek card which appears to use the r8169 driver.  The
machine is a samba server and when serving files to a local
Linux or Windows client, I only get approx 40-60 kbps. 
Write performance is fine though, in the tens of mbps and
scp, nfs, and ftp server all work well so it appears
specific to the Samba load.  However, when serving to more
than one client symoltaniously, performance goes up
dramatically, again into the tens of mbps or when there is
other network activity.

Shane, join the crowd :)  Try the fix I just re-posted over here:

http://www.spinics.net/lists/netdev/msg39244.html