Messages in this thread | | | Date | Wed, 15 Jun 2011 15:12:21 +0200 | From | Thomas Hellstrom <> | Subject | Re: [Linaro-mm-sig] [PATCH 08/10] mm: cma: Contiguous Memory Allocator added |
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On 06/15/2011 01:53 PM, Daniel Vetter wrote: > On Tue, Jun 14, 2011 at 20:30, Arnd Bergmann<arnd@arndb.de> wrote: > >> On Tuesday 14 June 2011 18:58:35 Michal Nazarewicz wrote: >> >>> Ah yes, I forgot that separate regions for different purposes could >>> decrease fragmentation. >>> >> That is indeed a good point, but having a good allocator algorithm >> could also solve this. I don't know too much about these allocation >> algorithms, but there are probably multiple working approaches to this. >> > imo no allocator algorithm is gonna help if you have comparably large, > variable-sized contiguous allocations out of a restricted address range. > It might work well enough if there are only a few sizes and/or there's > decent headroom. But for really generic workloads this would require > sync objects and eviction callbacks (i.e. what Thomas Hellstrom pushed > with ttm). >
Indeed, IIRC on the meeting I pointed out that there is no way to generically solve the fragmentation problem without movable buffers. (I'd do it as a simple CMA backend to TTM). This is exactly the same problem as trying to fit buffers in a limited VRAM area.
/Thomas
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