[dpdk-dev] Using multi-queue with RSS on X540 VF

[Bruce Richardson]

On Mon, Dec 15, 2014 at 10:47:40AM +0000, Bruce Richardson wrote:
> On Sat, Dec 13, 2014 at 01:44:36AM +0000, Anant Mudambi wrote:
> > Hi all,
> > I am using DPDK 1.7.0.
> > Qemu-KVM system with the Intel 10G X540 NIC; host has the Linux ixgbe PF driver and a guest is using a VF with the DPDK ixgbevf PMD (uio).
> > I am trying to configure multiple (2 for now) receive queues on the VF and use RSS.
> > I see packets coming only to queue 0 for some reason. Some questions about this:
> > 
> > 1] I see that most of the initial configuration to make multi-queue + RSS work is done in ixgbe_dev_mq_rx_configure()
> >      [e.g. Setting up the redirect table and the MRQC register]. However, only the non-VF ixgbe_dev_rx_init() calls the above function;
> >      ixgbevf_dev_rx_init() doesn't configure RSS-related hardware. Don't we need to do this configuration to use RSS on a VF?
> > 2] Even after configuring the RSS-related hardware in ixgbevf PMD, packets only come to queue 0. I printed out the RSS-type and RSS-hash-value
> >      fields from the write back Rx descriptor and they are both set to 0. So for some reason no RSS hash is being done for any packets.
> > 3] Has anyone seen this kind of configuration work (multi-queue + RSS + VF)? I have an X540 NIC but has this worked on any other NIC for anyone?
> > 4] Also any ideas on how to debug this problem further?
> > 
> > Thanks,
> > Anant
> 
> RSS redirection of traffic in a VF is not supported by the hardware, so you are
> pretty much stuck with all VF traffic going to queue 0. [Later hardware, such as
> 4x10G NICs e.g. "Intel® Ethernet Converged Network Adapters XL710" using the
> i40e driver should support RSS with VFs]
> 
> /Bruce

Actually, I see Changchun has posted a patch giving support for RSS use with VF's
so apparently some functionality is possible with 10G NICs such as the x540. There
may be some limitations with it, however, but I'll defer any further explanation
to him. :-)

/Bruce