On Mon, 19 Nov 2012 16:38:18 +0100 Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> wrote: > Hello, > > On 11/14/2012 11:58 PM, Andrew Morton wrote: > > On Mon, 12 Nov 2012 09:59:42 +0100 > > Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> wrote: > > > > > It has been observed that system tends to keep a lot of CMA free pages > > > even in very high memory pressure use cases. The CMA fallback for movable > > > pages is used very rarely, only when system is completely pruned from > > > MOVABLE pages, what usually means that the out-of-memory even will be > > > triggered very soon. To avoid such situation and make better use of CMA > > > pages, a heuristics is introduced which turns on CMA fallback for movable > > > pages when the real number of free pages (excluding CMA free pages) > > > approaches low water mark. > > ... > > > erk, this is right on the page allocator hotpath. Bad. > > Yes, I know that it adds an overhead to allocation hot path, but I found > no other > place for such change. Do You have any suggestion where such change can > be applied > to avoid additional load on hot path? Do the work somewhere else, not on a hot path? Somewhere on the page reclaim path sounds appropriate. How messy would it be to perform some sort of balancing at reclaim time? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>