PE2950 - Linux TCP Offload Engine (TOE) configuration

Tue Dec 18 14:08:21 CST 2007

TOE and Linux, always a bone of contention..

Some interesting articles to consider;

http://lwn.net/Articles/148697/

http://www.linux-foundation.org/en/Net:TOE

Only true way to disable TOE (as Terry rightly mentioned) is to remove
TOE key from mainboard (with care) - it's an RJ11 connector and a small
cream coloured "dollop", similar to that of a bon-bon that's been sucked
for about 20 minutes.. Sadly no option to disable the TOE at BIOS level,
only see if it's enabled/disabled, due to the presence of the TOE key.

TOE will never be "on" in the OS, as the *nix Broadcom driver does not
utilise TOE, and it's a driver orientated feature. TSO is obviously
enabled by the driver and working, I'm not sure whether this is going to
cause you problems or not, I would leave the settings as default and
benchmark the performance, then try disabling it and benchmark again to
know for sure.

"Cannot get device udp large send offload settings: Operation not
supported"
and
"Cannot get device generic segmentation offload settings: Operation not
supported"

-- this is telling you that TOE isn't active.

TX/RX checksumming is being offloaded to the NIC firmware, this isn't
TOE. It could however it could be argued that if the kernel network
stack isn't doing the checksumming, then the TCP/IP packets are being
checksummed at the NIC. I'm not sure if the raw packets are being
checksummed, or the TCP/IP packets, my knowledge doesn't strech that
far..

Hope this is of use..

Regards,

Nick

-----Original Message-----
From: linux-poweredge-bounces at dell.com
[mailto:linux-poweredge-bounces at dell.com] On Behalf Of Terry Gliedt
Sent: 18 December 2007 18:31
To: linux-poweredge-Lists
Subject: Re: PE2950 - Linux TCP Offload Engine (TOE) configuration

Right or wrong, when I see that TOE is available in BIOS, I open the PE 
machine up and remove the little RJxx plug so TOE is gone. It's never 
hurt and then I don't have any surprises. We only run Linux.

Gary Mansell wrote:
> Hi,
> 
> I have a PE2950 with on-board Broadcom network cards. I am trying to
> understand how best to configure them. It is my understanding the the
> Linux developers are strongly against TOE so I presume that it just
does
> not work on Linux - ie you don't have to do anything to disable it.
> 
> When I list the offload status on the card, I see the following:
> 
> [root at dfgsrv1 ~]# ethtool -k eth0
> Offload parameters for eth0:
> Cannot get device udp large send offload settings: Operation not
> supported
> Cannot get device generic segmentation offload settings: Operation not
> supported
> rx-checksumming: on
> tx-checksumming: on
> scatter-gather: on
> tcp segmentation offload: on
> udp fragmentation offload: off
> generic segmentation offload: off
> 
> This suggests to me that TOE is on ???
> 
> I guess this means that the card is set for TOE but the Linux OS will
> not do anything with it?
> 
> Is it OK to leave the params as they are or should I run the following
> line from /etc/rc.local ?
> 
> ethtool -K eth0 rx off tx off sg off tso off
> 
> 
> Any advise gladly received.
> 
> Regards
> 
> Gary
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