Bug#572201: forcedeth driver hangs under heavy load

[David Miller <davem@davemloft.net>]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Tue, 13 Apr 2010 16:42:21 +0200

> Le mardi 13 avril 2010 à 15:27 +0100, stephen mulcahy a écrit :
>> Ok, I've tried both of the following with my reproducer
>> 
>> 1. ethtool -K eth0 tso off
>> 
>> RESULT: reproducer causes multiple hosts to be come unresponsive on 
>> first run.
>> 
>> 2. ethtool -K eth0 tx off
>> 
>> RESULT: reproducer runs three times without any hosts becoming unresponsive.
>> 
>> -stephen
> 
> Thanks Stephen !
> 
> Now some brave fouls to check the 6410 lines of this driver ? ;)
> 
> Question of the day : Why TSO is broken in forcedeth ?
> Is it generically broken or is it broken for specific NICS ?

Do you really come to the conclusion that TSO is broken with the above
test results?

I would conclude that there is a TX checksumming issue, since merely
turning TSO off does not fix the problem whereas turning TX
checksumming off does.