Eric Dumazet wrote:

quoted

Is there an easy way to get this NUMA node from the application socket
descriptor?
    

Thats not easy, this information can change for every packet (think of
bonding setups, whith aggregation of devices on different NUMA nodes)
  

If we return a mask of cpus near the NIC, we could return the mask
containing cpus that are close to any of the devices that were
aggregated in this bonding setup.
If no bonding, it's fine. If bonding, the behavior looks acceptable to me.

We could add a getsockopt() call to peek this information from the next
data to be read from socket (returns node id where skb data is sitting,
hoping that NIC driver hadnt copybreak it (ie : allocate a small skb and
copy the device provided data on it before feeding packet to network stack))


  

quoted

Also, one question that was raised at the Linux Symposium is: how do you
know which processors run the receive queue for a specific connection ?
It would be nice to have a way to retrieve such information in the
application to avoid inter-node and inter-core/cache traffic.
    

All this depends on the fact you have multiqueue devices or not, and
trafic spreads on all queues or not.
  

Again, on a per-connection basis, you should know whether your packets
are going through a single queue or to all of them? If going to a single
queue, return a mask of cpus near this exact queue. If going to multiple
queues (or if you don't know), just sumup the cpumask of all queues.

Brice