Re: [RFC net-next v4 0/9] Add support for per-NAPI config via netlink

Joe Damato
2024-10-03T23:53:18Z

On Thu, Oct 03, 2024 at 04:29:37PM -0700, Stanislav Fomichev wrote:
> On 10/01, Joe Damato wrote:

[...]

> > 2. This revision seems to work (see below for a full walk through). Is
> > this the behavior we want? Am I missing some use case or some
> > behavioral thing other folks need?
>
> The walk through looks good!

Thanks for taking a look.

> > 3. Re a previous point made by Stanislav regarding "taking over a NAPI
> > ID" when the channel count changes: mlx5 seems to call napi_disable
> > followed by netif_napi_del for the old queues and then calls
> > napi_enable for the new ones. In this RFC, the NAPI ID generation
> > is deferred to napi_enable. This means we won't end up with two of
> > the same NAPI IDs added to the hash at the same time (I am pretty
> > sure).
>
>
> [..]
>
> > Can we assume all drivers will napi_disable the old queues before
> > napi_enable the new ones? If yes, we might not need to worry about
> > a NAPI ID takeover function.
>
> With the explicit driver opt-in via netif_napi_add_config, this
> shouldn't matter? When somebody gets to converting the drivers that
> don't follow this common pattern they'll have to solve the takeover
> part :-)

That is true; that's a good point. I'll let the RFC hang out on the
list for another day or two just to give Jakub time to catch up on
his mails ;) but if you all agree... this might be ready to be
resent as a PATCH instead of an RFC.