[dpdk-dev] Broken RSS hash computation on Intel 82574L

Jim Thompson jim at netgate.com
Tue Sep 1 17:19:23 CEST 2015


> On Sep 1, 2015, at 9:47 AM, Matthew Hall <mhall at mhcomputing.net> wrote:
> 
> On Tue, Sep 01, 2015 at 04:37:18PM +0200, Martin Drašar wrote:
>> Dne 1.9.2015 v 15:45 De Lara Guarch, Pablo napsal(a):
>>> 82574L NIC uses em PMD, which does not support more than 1 queue.
>>> Therefore RSS is disabled in the NIC and then you cannot have RSS hashes.
>>> 
>>> Thanks,
>>> Pablo
>> 
>> Hi Pablo,
>> 
>> that is an interesting information. I read the rationale in em_ethdev.c
>> and I was wondering, what would have to be done to enable RSS hash
>> computation on that card. I can live with just one RX queue, but hashes
>> would help me a lot. The computer which is using those NICs is not that
>> powerful and every bit of offloaded computation counts...
>> 
>> Thanks,
>> Martin
> 
> RSS calculations are used to direct packets across multiple RX queues. With 
> only one RX queue it cannot possibly increase performance by enabling it.

Well, there are other things you could use that hw-provided hash for…

(but point-taken)




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