[PATCH v12 02/12] net/tap: do not duplicate fd's

[Stephen Hemminger]

On Mon, 20 May 2024 18:46:30 +0100
Ferruh Yigit <ferruh.yigit at amd.com> wrote:

> On 5/2/2024 10:31 PM, Stephen Hemminger wrote:
> > The TAP device can use same file descriptor for both rx and tx queues.
> > This allows up to 8 queues (versus 4) to be used with secondary process.
> >   
> 
> It would be nice to briefly update where this limit comes from, as
> removing this limitation can be longer term solution for this issue.

Sure, the limit comes from a too low value in RTE_MP_MAX_FD_NUM (8)
It should have been set to the max Linux supports which is SCM_MAX_FD
(253).

But fixing it their breaks the ABI, and needs to wait for 24.11.
Impacts AF_XDP as well.

By not duplicating we can make TAP work with 8 queues and still
get MP support. Good idea anyway not to waste fd's.

> 
> > Bugzilla ID: 1381
> > Signed-off-by: Stephen Hemminger <stephen at networkplumber.org>
> >  
> 
> Can you please move the relevant release notes update to this patch?
> So we can distribute the release notes update to patches instead of
> dedicated update for it.
> 
> Except from above change,
> Acked-by: Ferruh Yigit <ferruh.yigit at amd.com>
>