Re: Add more lcores to application after rte_eal_init has been called

[David Marchand <david.marchand@redhat.com>]

On Wed, Feb 22, 2023 at 4:05 PM Stephen Hemminger
<stephen@networkplumber.org> wrote:
>
> On Wed, 22 Feb 2023 14:10:20 +0100
> Antonio Di Bacco <a.dibacco.ks@gmail.com> wrote:
>
> > I need to add some more cores to the application after the DPDK has
> > already been initialised.
> > Is it possible?
>
> No
>
> > For other resources like network cards, I managed to probe new cards
> > dynamically but don't understand how I can do the same for new lcores.
>
> You can start with lots of cores, but only use some of them in your
> application. The unused queues could wait on something like pthread_condition
> that is blocking.
>

If you really want to go with a dynamic approach, you could do like
OVS does which is to stop using EAL threads, but have everything in
your applications: create threads + set their cpu affinity + register
them as lcores.
That's the *easy* part.

Then, if you want to go and only configure the exact number of rxq/txq
wrt to your datapath threads, next is that you need to reconfigure the
existing ports when a change happens and you will need to stop your
existing datapath threads from pulling packets before reconfiguring
the ports.


Stephen description is probably the best/least effort.


-- 
David Marchand