On Thu, Oct 16, 2014 at 11:35 AM, Hui Zhu <zhuhui@xxxxxxxxxx> wrote: > In fallbacks of page_alloc.c, MIGRATE_CMA is the fallback of > MIGRATE_MOVABLE. > MIGRATE_MOVABLE will use MIGRATE_CMA when it doesn't have a page in > order that Linux kernel want. > > If a system that has a lot of user space program is running, for > instance, an Android board, most of memory is in MIGRATE_MOVABLE and > allocated. Before function __rmqueue_fallback get memory from > MIGRATE_CMA, the oom_killer will kill a task to release memory when > kernel want get MIGRATE_UNMOVABLE memory because fallbacks of > MIGRATE_UNMOVABLE are MIGRATE_RECLAIMABLE and MIGRATE_MOVABLE. > This status is odd. The MIGRATE_CMA has a lot free memory but Linux > kernel kill some tasks to release memory. I'm not very clear to this description, what issue do you try to solve? Make MIGRATE_CMA be the fallback of desired MIGRATE_UNMOVABLE? > This patch series adds a new function CMA_AGGRESSIVE to make CMA memory > be more aggressive about allocation. > If function CMA_AGGRESSIVE is available, when Linux kernel call function > __rmqueue try to get pages from MIGRATE_MOVABLE and conditions allow, > MIGRATE_CMA will be allocated as MIGRATE_MOVABLE first. If MIGRATE_CMA > doesn't have enough pages for allocation, go back to allocate memory from > MIGRATE_MOVABLE. I don't think so. That will cause MIGRATE_CMA depleted prematurely, and when a user(such as camera) wants CMA memory, he will not get the wanted memory. > Then the memory of MIGRATE_MOVABLE can be kept for MIGRATE_UNMOVABLE and > MIGRATE_RECLAIMABLE which doesn't have fallback MIGRATE_CMA. I don't think this is the root cause of oom. But I am interested in the CMA shrinker idea, I will follow this mail. Thanks for your work, add some test data will be better. > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- 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>