Re: [Question] Generic way to retrieve IRQ number of Tx/Rx queue

[Daniel Sedlak]

On 1/13/25 10:15 PM, Jakub Kicinski wrote:
> On Fri, 10 Jan 2025 10:07:18 +0100 Daniel Sedlak wrote:
> > Hello,
> > I am writing an affinity scheduler in the userspace for network cards's
> > Tx/Rx queues. Is there a generic way to retrieve all IRQ numbers for
> > those queues for each interface?
> >
> > My goal is to get all Tx/Rx queues for a given interface, get the IRQ
> > number of the individual queues, and set an affinity hint for each
> > queue. I have tried to loop over /proc/interrupts to retrieve all queues
> > for an interface in a hope that the last column would contain the
> > interface name however this does not work since the naming is not
> > unified across drivers. My second attempt was to retrieve all registered
> > interrupts by network interface from
> > /sys/class/net/{interface_name}/device/msi_irqs/, but this attempt was
> > also without luck because some drivers request more IRQs than the number
> > of queues (for example i40e driver).
>
> We do have an API for that
> https://docs.kernel.org/next/networking/netlink_spec/netdev.html#napi
> but unfortunately the driver needs to support it, and i40e currently
> doesn't:

Thank you for the link, I somehow missed that part of netlink…

> $ git grep --files-with-matches  netif_napi_set_irq
> drivers/net/ethernet/amazon/ena/ena_netdev.c
> drivers/net/ethernet/broadcom/bnxt/bnxt.c
> drivers/net/ethernet/broadcom/tg3.c
> drivers/net/ethernet/google/gve/gve_utils.c
> drivers/net/ethernet/intel/e1000/e1000_main.c
> drivers/net/ethernet/intel/e1000e/netdev.c
> drivers/net/ethernet/intel/ice/ice_lib.c
> drivers/net/ethernet/intel/igc/igc_main.c
> drivers/net/ethernet/mellanox/mlx4/en_cq.c
> drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> drivers/net/ethernet/meta/fbnic/fbnic_txrx.c
>
> Should be easy to add. Let me CC the Intel list in case they already
> have a relevant change queued for i40e..

Thank you for directions, will check Intel's mailing list and poke 
around with implementing that.

Daniel