On Fri, Oct 24, 2014 at 1:25 PM, Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> wrote: > On Thu, Oct 16, 2014 at 11:35:47AM +0800, Hui Zhu 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. >> >> 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. >> Then the memory of MIGRATE_MOVABLE can be kept for MIGRATE_UNMOVABLE and >> MIGRATE_RECLAIMABLE which doesn't have fallback MIGRATE_CMA. > > Hello, > > I did some work similar to this. > Please reference following links. > > https://lkml.org/lkml/2014/5/28/64 > https://lkml.org/lkml/2014/5/28/57 > I tested #1 approach and found the problem. Although free memory on > meminfo can move around low watermark, there is large fluctuation on free > memory, because too many pages are reclaimed when kswapd is invoked. > Reason for this behaviour is that successive allocated CMA pages are > on the LRU list in that order and kswapd reclaim them in same order. > These memory doesn't help watermark checking from kwapd, so too many > pages are reclaimed, I guess. This issue can be handle with some change around shrink code. I am trying to integrate a patch for them. But I am not sure we met the same issue. Do you mind give me more info about this part? > > And, aggressive allocation should be postponed until freepage counting > bug is fixed, because aggressive allocation enlarge the possiblity > of problem occurence. I tried to fix that bug, too. See following link. > > https://lkml.org/lkml/2014/10/23/90 I am following these patches. They are great! Thanks for your work. Best, Hui > > Thanks. > > -- > 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> -- 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>