On Wed, Oct 29, 2014 at 10:43 PM, Vlastimil Babka <vbabka@xxxxxxx> wrote: > On 10/16/2014 10:55 AM, Laura Abbott wrote: >> >> On 10/15/2014 8:35 PM, Hui Zhu wrote: >> >> It's good to see another proposal to fix CMA utilization. Do you have >> any data about the success rate of CMA contiguous allocation after >> this patch series? I played around with a similar approach of using >> CMA for MIGRATE_MOVABLE allocations and found that although utilization >> did increase, contiguous allocations failed at a higher rate and were >> much slower. I see what this series is trying to do with avoiding >> allocation from CMA pages when a contiguous allocation is progress. >> My concern is that there would still be problems with contiguous >> allocation after all the MIGRATE_MOVABLE fallback has happened. > > > Hi, > > did anyone try/suggest the following idea? > > - keep CMA as fallback to MOVABLE as is is now, i.e. non-agressive > - when UNMOVABLE (RECLAIMABLE also?) allocation fails and CMA pageblocks > have space, don't OOM immediately, but first try to migrate some MOVABLE > pages to CMA pageblocks, to make space for the UNMOVABLE allocation in > non-CMA pageblocks > - this should keep CMA pageblocks free as long as possible and useful for > CMA allocations, but without restricting the non-MOVABLE allocations even > though there is free memory (but in CMA pageblocks) > - the fact that a MOVABLE page could be successfully migrated to CMA > pageblock, means it was not pinned or otherwise non-migratable, so there's a > good chance it can be migrated back again if CMA pageblocks need to be used > by CMA allocation > - it's more complex, but I guess we have most of the necessary > infrastructure in compaction already :) I think this idea make CMA allocation part become complex but make balance and shrink code become easy because it make CMA become real memory. I just worry about the speed of migrate memory with this idea. :) Thanks, Hui > > Thoughts? > Vlastimil > >> Thanks, >> Laura >> > > -- > 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>