igb performance/load udp issue

[Clint]

On Wed, 21 Dec 2011 16:34:56 +0100, Luigi Rizzo wrote:
> On Wed, Dec 21, 2011 at 08:04:54AM -0700, Clint wrote:
>> On Tue, 20 Dec 2011 22:46:46 -0800, Jack Vogel wrote:
>> >I was fighting with UDP issues before the latest checkin, so you
>> >should
>> >look at THAT version, 2.3.1 in HEAD please.
>> >
>> >Jack
>> >
>>
>> I'm actually running the HEAD version now, but my problems still
>> persist.  I did notice that the excessive load is now spread across
>> multiple cores where before it was isolated to one core at a time.  
>> This
>> version also doesn't suffer from the horrible performance I 
>> experienced
>> with v2.2.5.
>
> as someone mentioned, it may have to do with the sender
> using multiple queues thus causing reordering in the frames,
> which then the receiver has to sort (and often, the receive
> queue is a list so O(N) complexity per packet.)
>
> Can you run the igb driver with just a single queue ?
> In the bootloader, or before loading the module using "kenv", you
> should set
>
> 	hw.igb.num_queues = 1
>
> This should prevent gratuitous reordering and perhaps fix
> your performance.
>
> cheers
> luigi

I've already tried that as well, but with the v2.0.3 driver, didn't 
help.  I'll try it again with the HEAD driver tonight.

Thanks,
Clint