Re: [Linaro-mm-sig] [PATCH 02/10] lib: genalloc: Generic allocatorimprovements

[Jordan Crouse]

On 06/10/2011 06:52 AM, Alan Cox wrote:
> > I plan to replace it with lib/bitmap.c bitmap_* based allocator (similar like
> > it it is used by dma_declare_coherent_memory() and friends in
> > drivers/base/dma-coherent.c). We need something really simple for CMA area
> > management.
> >
> > IMHO allocate_resource and friends a bit too heavy here, but good to know
> > that such allocator also exists.
>
> Not sure I'd class allocate_resource as heavyweight but providing it's
> using something that already exists rather than inventing yet another
> allocator.
>
> This wants dealing with before it goes upstream though so the chaneges in
> lib/*c etc never have to reach mainline and then get changed back.

Even if CMA doesn't end up using genalloc, there are existing consumers of
the API and I think the _aligned function has value.

I agree that allocate_resource isn't overly heavy, but comparatively genalloc
is really simple and lightweight for a driver to manage a contiguous address
space without a lot of extra thought. I think both APIs serve slightly
different masters, but if somebody thought about it long enough there could
be some consolidation (same goes for the internal guts of
dma_declare_coherent_memory).

I agree with Michal - if genalloc goes deprecated, then so be it, but as
long as it lives, I think its useful to get these functions upstream.

Jordan
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