On Tue, Apr 18, 2023 at 03:12:57PM -0400, Johannes Weiner wrote: > Currently, capturing only works on matching orders and matching > migratetypes. However, if capturing is initially skipped on the > migratetype, it's possible that merging continues up to a full > pageblock, in which case the migratetype is up for grabs again. > > Allow capturing to grab smaller chunks from claimed pageblocks, and > expand the remainder of the block back onto the freelists. > > Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx> No objections other than we're still in the preparation phase and the series needs to be split. Out of curiousity, how often does this actually trigger in practice? I ask because superficially, I would expect capture to happen while pages are being merged and I'm not sure how much this actually helps. If anything the anomaly would be merging !MOVABLE types, capturing one pageblock and leaving the adjacent block eligible for splitting as UNMOVABLE/RECLAIMABLE which is not necessarily desirable. I nagged about the splitting already but ideally there would be supporting data for all the incremental improvements before a major modification is made to fragmentation avoidance. That way, even if the fragmentation avoidance changes have side-effects, the incremental changes stand alone. -- Mel Gorman SUSE Labs
