Hi Krzysztof, On 09/11/2013 04:58 PM, Krzysztof Kozlowski wrote: > Hi, > > Currently zbud pages are not movable and they cannot be allocated from CMA > (Contiguous Memory Allocator) region. These patches add migration of zbud pages. > I agree that the migration of zbud pages is important so that system will not enter order-0 page fragmentation and can be helpful for page compaction/huge pages etc.. But after I looked at the [patch 4/5], I found it will make zbud very complicated. I'd prefer to add this migration feature later until current version zswap/zbud becomes better enough and more stable. Mel mentioned several problems about zswap/zbud in thread "[PATCH v6 0/5] zram/zsmalloc promotion". Like "it's clunky as hell and the layering between zswap and zbud is twisty" and "I think I brought up its stalling behaviour during review when it was being merged. It would have been preferable if writeback could be initiated in batches and then waited on at the very least.. It's worse that it uses _swap_writepage directly instead of going through a writepage ops. It would have been better if zbud pages existed on the LRU and written back with an address space ops and properly handled asynchonous writeback." So I think it would be better if we can address those issues at first and it would be easier to address these issues before adding more new features. Welcome any ideas. -- Regards, -Bob -- 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>