Thanks !
I Appreciate your answer.
On Fri, Oct 14, 2016 at 11:59 PM, Alexander Duyck wrote:
> On Fri, Oct 14, 2016 at 8:47 AM, Tal Abudi wrote:
> > Hi All
> > Maybe a silly question.. But...
> > When testing high performance (packet-rate) on a system with igb/ixgbe
> > nics, is there difference if i turn multi queue off or I set each queues
> > affinity to the same CPU ?
> >
> > My hunch says that MQ off (single queue) is better since the controller
> > doesn't need to select the right queue for each RX/TX packet, but maybe
> > it's negligible...
> >
> > Thanks,
> > Tal Abudi
> >
>
> The hardware itself doesn't really care how many queues are being
> used, however it can impact PCIe bus efficiency.
>
> For igb the impact would be negligable on everything 82580 and newer,
> on 82576 there is some impact with small packets due to descriptor
> caching and limited PCIe throughput. For ixgbe you might notice a
> difference if you are handling small packets in an accelerated
> environment with DPDK. Specifically you can achieve 64B packet line
> rate with 1 queue on 82599 and newer adapters supported by ixgbe.
> However as you add additional queues the throughput will drop as the
> descriptor fetching overhead for Rx will increase as blocks of packets
> become interleaved between queues resulting in fewer descriptors being
> fetched per read request.
>
> Hope that helps.
>
> - Alex
>
--
Best regards,
Tal Abudi
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