Gigabit Ethernet w/Jumbo Frames

[Steve Kargl]

On Tue, Jun 26, 2007 at 05:33:46PM -0700, george+freebsd at m5p.com wrote:
> I'm having poor luck trying to use NFS over a gigabit ethernet using
> jumbo frames.  By all indications, my switch (Netgear GS608) forwards
> jumbo frames with no difficulty, but my Realtek 8169-based cards seem
> unreceptive to the idea, giving many watchdog timeouts and other
> obscure log messages.  One server is amd64 and my clients are i386,
> but I think I've ruled that out as the problem because I see errors
> evern with an i386 server.  So I strongly suspect my network cards at
> the moment.  What gigabit ethernet cards do you use for reliable
> performance with jumbo frames?                -- George Mitchell
> 

Are you setting any sysctl tunables?  There have been recent
reports of watchdog timeout problems with xl, bge, and em devices.
I've manage to work around the timeout on bge with 

net.inet.tcp.sendspace=131072
net.inet.tcp.recvspace=131072
net.inet.tcp.path_mtu_discovery=0
net.inet.udp.recvspace=65536
net.inet.raw.recvspace=16384
hw.pci.enable_msix=0
hw.pci.enable_msi=0
kern.ipc.nmbclusters=50000
kern.timecounter.hardware=ACPI-fast

-- 
Steve