Re: IRQ assignment for queues

On Thu, Apr 22, 2021 at 3:14 AM Zvi Effron <[email protected]> wrote:
>
> On Tue, Apr 20, 2021 at 11:57 PM Srivats P <[email protected]> wrote:
> >
> > Hi,
> >
> > Not a XDP question, but more generic about IRQ assignment for queues.
> >
> > For a NIC which has separate RX and TX queues (no COMBINED queues), I
> > see in /proc/interrupts that only 1 IRQ is assigned.
> >
> > ...
> >
> > srivatsp@EXA8:~$ cat /proc/interrupts | grep enp5s0f1
> >  73:          0          2          0          0   ITS-MSI 2623488
> > Edge      enp5s0f1-rxtx-0
> >  89:          0          0          0          0   ITS-MSI 2623504
> > Edge      enp5s0f1-rbdr-0
> >  92:          0          0          0          0   ITS-MSI 2623507
> > Edge      enp5s0f1-qset-err-0
> >
> > Is the IRQ for the RX queue or TX queue or both? Does Tx need an IRQ?
>
> I see the IRQ name has "rxtx" in it. From my experience, that's the
> same type of designation used for combined queues, and indicates that
> the IRQ is for both RX and TX.

I guessed as much (based on i40e combined TxRx queues experience), but
wanted to confirm.

> I'm not sure which driver you're using,

This output and query was for the Cavium ThunderX nic_vf driver specifically.

> though, and my experience is mostly with i40e and ena drivers, so it
> could be incorrect when applied to your case.
>
> --Zvi