Re: TSP on em makes send of streams very slow

Jack Vogel wrote:
> On 9/21/07, Artem Kuchin <matrix_at_itlegion.ru> wrote:
>> Hello!
>>
>> Here is what i have experienced today.
>>
>> I just installed  7.0-CURRENT (cvsed and build on 2007/09/20)
>> on a PRODUCTION web server
>> (because, IHMO, this current is stable enough and i like
>> too much :)
>>
>> This is intel MB with two built-in em intefaces.
>>
>> I sshed to the server.
>> While i was in plain shell everything was fine, but when i
>> stared midnight commander i saw how it very slowly draws
>> scren part by part. It took about 3 monutes to almost
>> completely draw a screen when i got disconnected. I tied again
>> - the same. Then i connected via ftp and uploaded 10MB file
>> at 900KB/sec. When i tried to download it back  i got about
>> 500 *BYTES*/sec and the got disconnected in a couple of minutes.
>>
>> Ping was just find, even flood ping from the server on the save
>> switch with 15000 packets was fine (just one dot on the left).
>>
>> I went also crazy already when i desided to compare interface params
>> with another server with em NICs.
>>
>> The dfference is that this is has the following options (by DEFAULT,
>> i did not turn it on):
>>
>> VLAN_HWCSUM,TSO4
>>
>> I've read about TSO on 'man ifconfig' and just for kicks decided
>> to turn it off. VOILA!!! In a seconds send speed was up to 10 MBYTES/sec!
>>
>> I have googled about 'em tso slow ' etc.. and found a couple of seemingly
>> the same problem dated back 2006. Is it supposed to be solved by now?
>> What IS the problem with TSO?
> 
> 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 :)

So the card can't handle it?  Note that the OP says it was enabled 
automatically.

I wouldn't necessarily expect it to give a performance benefit, but it 
shouldn't destroy performance to that extent either.  There seems to be 
a real problem to be addressed here.

Kris