Messages in this thread | | | Date | Fri, 26 Jun 2015 13:22:07 +0200 | From | Vlastimil Babka <> | Subject | Re: [RFC PATCH 00/10] redesign compaction algorithm |
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On 06/26/2015 04:14 AM, Joonsoo Kim wrote: > 2015-06-26 3:56 GMT+09:00 Vlastimil Babka <vbabka@suse.cz>: >>> on non-movable would be maintained so fallback doesn't happen. >> >> There's nothing that guarantees that the migration scanner will be emptying >> unmovable pageblock, or am I missing something? > > As replied to Mel's comment, as number of unmovable pageblocks, which is > filled by movable pages due to this compaction change increases, > possible candidate reclaimable/migratable pages from them also increase. > So, at some time, amount of used page by free scanner and amount of > migrated page by migration scanner would be balanced. > >> Worse, those pageblocks would be >> marked to skip by the free scanner if it isolated free pages from them, so >> migration scanner would skip them. > > Yes, but, next iteration will move out movable pages from that pageblock > and freed pages will be used for further unmovable allocation. > So, in the long term, this doesn't make much more fragmentation.
Theoretically, maybe. I guess there's not much point discussing it further, until there's data from experiments evaluating the long-term fragmentation (think of e.g. the number of mixed pageblocks you already checked in different experiments).
> Thanks. >
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