On 09/01/2015 05:47 PM, Matthew Hall wrote: > On Tue, Sep 01, 2015 at 04:37:18PM +0200, Martin Dra?ar 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. >
As an example, seastar uses the RSS hash computed by the NIC to select a core to process on, if the number of hardware queues is smaller than the number of cores.