Re: [PATCH] net/tap: allow more that 4 queues

[Stephen Hemminger <stephen@networkplumber.org>]

On Thu, 7 Mar 2024 10:25:48 +0000
Ferruh Yigit <ferruh.yigit@amd.com> wrote:

> > I got 4 queues setup, but looks like they are trash in secondary.
> > Probably best to revert this and fix it by bumping RTE_MP_MAX_FD_NUM.
> > This is better, but does take some ABI issue handling.
> >  
> 
> We can increase RTE_MP_MAX_FD_NUM but still there will be a limit.
> 
> Can't it be possible to update 'rte_mp_sendmsg()' to support multiple
> 'rte_mp_sendmsg()' calls in this patch?
> 
> Also need to check if fds size is less than 'RTE_PMD_TAP_MAX_QUEUES'
> with multiple 'rte_mp_sendmsg()' call support.

Kernel allows up to 253 fd's to be passed.
So for tap that would limit it to 126 queues; because TAP dups the
fd's for rx and tx but that could be fixable.

Tap should have a static assert about max queues and this as well.

Increasing RTE_MP_MAX_FD_NUM would also fix similar issues in af_xdp PMD
and when af_packet gets MP support.