Re: [PATCH 2/2] ixgbe: don't override mbuf buffer length

[Jean-Mickael Guerin <jean-mickael.guerin-pdR9zngts4EAvxtiuMwx3w@public.gmane.org>]

>> Which makes me think, that we probably shouldn't overwrite buf_len by rxq->mbuf_initializer.
>>
> I believe that it is perfectly safe to do so. All buffers from a mempool are meant
> to be the same size, therefore reading the length of one buffer should tell you
> what size all buffers are. If we do hit a scenario where we do need to support
> variable size buffers from a single mempool, we can do that via the older unoptimized
> code paths, I think, since it's a definite edge case.
>

I agree, and there is a place to store some values unique for all mbufs 
in a pool:

struct rte_pktmbuf_pool_private {
         uint16_t mbuf_data_room_size; /**< Size of data space in each 
mbuf.*/
};

We could add a new field mbuf_buf_len here, it looks definitely better 
than new callbacks in rte_mempool.

What do you think?