rtems-libbsd - UMA, Pages and slabs

[Gedare Bloom]

On Thu, Apr 19, 2012 at 2:57 PM, Joel Sherrill
<joel.sherrill at oarcorp.com> wrote:
> Hi
>
> Jennifer removed the RTEMS specific UMA file and
> switched us to the BSD UMA file with all unreferenced
> routines disabled and some paths which look unneeded
> disabled.
>
> At the bottom of the UMA code logically, it  allocates
> pages which are treated as slabs from which allocations
> are made for each UMA pool.
>
> We don't have pages so we are stuck at how best
> to address the following:
>
> + page_alloc/page_free in uma_core.c.
>   - how/what to allocate.
> + uma_find_refcnt() in uma_core.c uses a reference
>   count inside the page that was allocated as a slab.
>   This method is needed but
> + vtoslab in uma_find_refcnt()
>
> Do we need to implement our own page_free/page_alloc
> which are more than a  keep a list of "pages" allocated
> and then be able to track the refcnt?
>
What are the allocation requirements? We should think about
implementing an "allocation" score manager that can satisfy all the
various allocators that are sitting around... regions, partitions, the
new rbheap, this UMA pool..

> This may involve also replacing keg_alloc_slab()
> and startup_alloc() before we are done because
> we only have one way to allocate "slabs" and it should
> work anytime we need one.
>
> This doesn't necessarily seem like a lot of code that
> would be RTEMS specific but it has to be right. :)
>
> --
> Joel Sherrill, Ph.D.             Director of Research&   Development
> joel.sherrill at OARcorp.com        On-Line Applications Research
> Ask me about RTEMS: a free RTOS  Huntsville AL 35805
>    Support Available             (256) 722-9985
>
>
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