[lwip-devel] mem(p) allocator change request

[christiaan . simons]

Hi,

A few weeks back there was a discussion
about the lwip memory allocator(s).
This is an interesting one since all complex
protocols like TCP or SNMP need some
form of dynamic memory.

A general purpose allocator will typically
produce some memory fragmentation
which is unacceptable for embedded systems.

A pool allocator avoids this issue by
using fixed size blocks. I don't see
a reason to remove this allocator
as Luke proposed. Other algorithms like
the buddy allocator might be more space
efficient though.

I would like to post the following change request:

Change the memp allocator to accept
externally allocated pools of arbitrary
size and type  blocks.
(inspired by the uC/OS-II allocator...)

In this scheme each module (like TCP
or SNMP) needs to provide one or more pools.

This removes the dependencies on structs
from various pieces of the stack.
Sub allocating the blocks can be done
on a per module basis.

I'm happy to look into this
(if there are no objections).
It requires some changes in various
bits and is somewhat intrusive.

Christiaan Simons

Axon Digital Design
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