TSP on em makes send of streams very slow
Artem Kuchin
matrix at itlegion.ru
Sun Sep 23 02:31:59 PDT 2007
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
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