Re: [lwip-members] Pbufs

[Kieran Mansley]

On Wed, 26 Mar 2003, Jani Monoses wrote:
> I thought about pbufs lately and I think that some ideas that were
> raised before are worth noting and implementing sometime. Leon's
> suggestion of pools with sizes of 2^X and Kieran's payload /header
> separation both seem improvements. I thought of having only pool type
> pbufs with special predefined sizes (would this not be as good as your
> mem_pool for header Kieran?) and also with application definiable sizes.
>
> An app or lwip submodule could register_pbuf_pool(struct pbuf_pool *)
> where pbuf_pool would define pool size/pool count, operations suchs as
> pbuf_alloc free etc. This way RAM pbufs could be implemented over pool
> pbufs. For pools such as current only the size would be app defined the
> operations would be the same So you can have 2^X or ethernet_hdr_sized
> pbufs. And apps and lwip modules wuld be changed to allocate from their
> respective pools. This would ease on locking too for sure.

The only drawback with fragmenting into many pools like this (it will make
it easier in terms of locking that's for sure) is the situation where one
pool runs out of memory but another has loads free.  It's a change in
philosophy away from the "lwIP is a really low memory usage stack".  This
doesn't bother me particularly, but it might others.

Kieran