Messages in this thread |  | | Date | Thu, 20 Feb 2014 17:49:50 +0100 | From | Vlastimil Babka <> | Subject | Re: [PATCH v2 2/5] mm/compaction: do not call suitable_migration_target() on every page |
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On 02/14/2014 07:54 AM, Joonsoo Kim wrote: > suitable_migration_target() checks that pageblock is suitable for > migration target. In isolate_freepages_block(), it is called on every > page and this is inefficient. So make it called once per pageblock. > > suitable_migration_target() also checks if page is highorder or not, > but it's criteria for highorder is pageblock order. So calling it once > within pageblock range has no problem. > > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
> diff --git a/mm/compaction.c b/mm/compaction.c > index bbe1260..0d821a2 100644 > --- a/mm/compaction.c > +++ b/mm/compaction.c > @@ -245,6 +245,7 @@ static unsigned long isolate_freepages_block(struct compact_control *cc, > unsigned long nr_strict_required = end_pfn - blockpfn; > unsigned long flags; > bool locked = false; > + bool checked_pageblock = false; > > cursor = pfn_to_page(blockpfn); > > @@ -275,8 +276,16 @@ static unsigned long isolate_freepages_block(struct compact_control *cc, > break; > > /* Recheck this is a suitable migration target under lock */ > - if (!strict && !suitable_migration_target(page)) > - break; > + if (!strict && !checked_pageblock) { > + /* > + * We need to check suitability of pageblock only once > + * and this isolate_freepages_block() is called with > + * pageblock range, so just check once is sufficient. > + */ > + checked_pageblock = true; > + if (!suitable_migration_target(page)) > + break; > + } > > /* Recheck this is a buddy page under lock */ > if (!PageBuddy(page)) >
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