From mboxrd@z Thu Jan 1 00:00:00 1970 From: thellstrom@vmware.com (Thomas Hellstrom) Date: Wed, 15 Jun 2011 15:12:21 +0200 Subject: [Linaro-mm-sig] [PATCH 08/10] mm: cma: Contiguous Memory Allocator added In-Reply-To: References: <1307699698-29369-1-git-send-email-m.szyprowski@samsung.com> <201106141803.00876.arnd@arndb.de> <201106142030.07549.arnd@arndb.de> Message-ID: <4DF8AFB5.10205@vmware.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 06/15/2011 01:53 PM, Daniel Vetter wrote: > On Tue, Jun 14, 2011 at 20:30, Arnd Bergmann 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