RFC : Heap management using TLSF

[timcussins at eml.cc (Tim)]

On Tue, 2008-07-29 at 08:25 -0500, Joel Sherrill wrote:
> I would like to make sure I understand why this algorithm
> is better.  And we definitely want to ensure that we have
> the same type of statistics and error checking information
> available in TLSF.  It would also be great to be able to walk the heap
> and get other information via the RTEMS gdb macros.
> 

Yeah, no problem :)

I'll be honest, I was talked into TLSF when I got back from 2 months of
holiday this year, having missed the previous discussion that took
place, so I basically put my hand up to do the work.

I've had a stab at transplanting TLSF into the tree, and we're using it
on a development branch, and giving it as much exposure as we can - no
problems so far.

The transplant includes stats, 95% complete. No GDB macros as yet
though.

> With any luck, the limited way the heap API is easy enough to just
> replace with another implementation. 
> 
> The only other gotcha in this is that the Classic API Region
> and ITRON API memory pools use the heap so we have to
> be sure we get the published features on those.
> 
> Basically you are looking to replace code that has already
> been overhauled once in the life of RTEMS but we have
> a fair amount of aids and APIs built around it, so we don't
> want to lose any capabilities.

Understood. In a couple of weeks I'll be back on this, and first thing
will be some benchmarks to quantify any performance gains associated
with moving to TLSF.

Cheers,
Tim