Re: TSP on em makes send of streams very slow

Jack Vogel wrote:
> On 9/22/07, Artem Kuchin <matrix_at_itlegion.ru> wrote:
>>> TSO is for some environments, it isn't gonna be useful at 100Mb
>>> (which you are), it can be useful at 1Gb but not always, when you
>>> get to 10G its
>>> a HUGE benefit.
>>> 
>>> Just cuz you can shoot yourself in the foot doesn't mean the gun
>>> has a problem :)
>> 
>> But wait, i did not shoot myself. I have been shot by the driver w/o
>> any preliminary warning. TSO4 was enabled by DEFAULT (i did not
>> enable it), 
>> so anybody can be in my place if used the same driver on the similar
>> hardware (which is plenty).
>> 
>> So, i think this is a problem which really need to be addressed.
> 
> It is on by default because it the majority of cases its a benefit,
> you found it to be a problem and turned it off, your problem is
> solved. 
> 
> I admit, at one point I considered disabling it automatically for
> anything under Gig speed, but a large community has used this driver
> with this feature for over a year, no one has lobbied to have to
> disabled, so I have not.
> 
> If there are others who think this would be a good idea, speak up, and
> I will do so.
> 

Disable it by default is not actually the point. There are three points:

1) I have wasted half a work day to figure it all out

2) I expect at least network part of *FREEBSD* OS to work right 
out of the box

3) Even having it enabled must not cause drop to 800 bytes/second
on send. This is clearly a bug. I don;t know if it is hardware of software bug
but it must be addressed in the driver anyway.

Or, as an option there must be a big waving banner somewhere where
noone can miss it saying: "If you have crazy drop in network send perfomance
disable TSO on your NIC via ifconfig".

--
Regards,
Artem