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 :)
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>