Re: [e1000 2.6 10/11] TxDescriptors -> 1024 default

[Ben Greear <greearb@candelatech.com>]

Jeff Garzik wrote:
> Feldman, Scott wrote:
> 
>> * Change the default number of Tx descriptors from 256 to 1024.
>>   Data from [ricardoz@us.ibm.com] shows it's easy to overrun
>>   the Tx desc queue.
> 
> 
> 
> All e1000 patches applied except this one.
> 
> Of _course_ it's easy to overrun the Tx desc queue.  That's why we have 
> a TX queue sitting on top of the NIC's hardware queue.  And TCP socket 
> buffers on top of that.  And similar things.
> 
> Descriptor increases like this are usually the result of some sillyhead 
> blasting out UDP packets, and then wondering why he sees packet loss on 
> the local computer (the "blast out packets" side).

Erm, shouldn't the local machine back itself off if the various
queues are full?  Some time back I looked through the code and it
appeared to.  If not, I think it should.

> 
> You're just wasting memory.
> 
>     Jeff
> 
> 
> 


-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com