Re: Dropped packets mapping IRQs for adjusted queue counts on i40e

On Sun, May 2, 2021 at 1:16 PM T K Sourabh <[email protected]> wrote:
>
> On Sat, May 1, 2021 at 11:26 PM Zvi Effron <[email protected]> wrote:
> >
> > I am wondering if not having the matching queues for the ingress
> > interface and egress interface on the same cores might be a
> > contributing factor?
> I haven't tested but you could give it a try to see if packet drop happens.

I have now tested matching the IRQs for queue N on both the ingress
and egress interfaces so they are on the same core. (Queue 0 for
ingress and egress are on the same core, the same for queue 1 on each,
etc, but queue 0 and queue 1 are on different cores). This did not
resolve the packet loss. I'm at a loss for what could be causing the
packet loss. It's clearly something to do with the IRQ remapping, as
all I need to do to remove the loss is comment out the write to the
smp_affinity files.

I'm suspecting it's something with how XDP_REDIRECT is implemented in
the i40e driver, but I don't know if this is a) cross driver behavior,
b) expected behavior, or c) a bug.

--Zvi