From mboxrd@z Thu Jan 1 00:00:00 1970 From: peterz@infradead.org (Peter Zijlstra) Date: Thu, 26 Aug 2010 10:18:57 +0200 Subject: [PATCH/RFCv4 0/6] The Contiguous Memory Allocator framework In-Reply-To: References: <1282310110.2605.976.camel@laptop> <20100825155814.25c783c7.akpm@linux-foundation.org> Message-ID: <1282810737.1975.240.camel@laptop> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, 2010-08-26 at 04:40 +0200, Micha? Nazarewicz wrote: > I think that the biggest problem is fragmentation here. For instance, > I think that a situation where there is enough free space but it's > fragmented so no single contiguous chunk can be allocated is a serious > problem. However, I would argue that if there's simply no space left, > a multimedia device could fail and even though it's not desirable, it > would not be such a big issue in my eyes. > > So, if only movable or discardable pages are allocated in CMA managed > regions all should work well. When a device needs memory discardable > pages would get freed and movable moved unless there is no space left > on the device in which case allocation would fail. If you'd actually looked at the page allocator you'd see its capable of doing exactly that! I has the notion of movable pages, it can defragment free space (called compaction). Use it!