On 9 Feb 2023, at 5:11, Yajun Deng wrote: > There is no need to execute the next loop if it not return in the first > loop. So add a break at the end of the loop. Can you explain why? If it is the case, MIGRATE_UNMOVABLE cannot fall back to MIGRATE_MOVABLE? And MIGRATE_MOVABLE cannot fall back to MIGRATE_UNMOVABLE? And MIGRATE_RECLAIMABLE cannot fall back to MIGRATE_MOVABLE? > > At the same time, add !migratetype_is_mergeable() before the loop and > reduce the first index size from MIGRATE_TYPES to MIGRATE_PCPTYPES in > fallbacks array. You sent a patch: https://lore.kernel.org/all/20230203100132.1627787-1-yajun.deng@xxxxxxxxx/T/#u, why not squash this one into that? Why do we need two separate small patches working on the same code? Thanks. > > Signed-off-by: Yajun Deng <yajun.deng@xxxxxxxxx> > Acked-by: Vlastimil Babka <vbabka@xxxxxxx> > --- > include/linux/mmzone.h | 2 +- > mm/page_alloc.c | 11 +++++------ > 2 files changed, 6 insertions(+), 7 deletions(-) > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index ab94985ee7d9..0a817b8c7fb2 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -85,7 +85,7 @@ static inline bool is_migrate_movable(int mt) > * Check whether a migratetype can be merged with another migratetype. > * > * It is only mergeable when it can fall back to other migratetypes for > - * allocation. See fallbacks[MIGRATE_TYPES][3] in page_alloc.c. > + * allocation. See fallbacks[][] array in page_alloc.c. > */ > static inline bool migratetype_is_mergeable(int mt) > { > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 1113483fa6c5..536e8d838fb5 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -2603,7 +2603,7 @@ struct page *__rmqueue_smallest(struct zone *zone, unsigned int order, > * > * The other migratetypes do not have fallbacks. > */ > -static int fallbacks[MIGRATE_TYPES][MIGRATE_PCPTYPES - 1] = { > +static int fallbacks[MIGRATE_PCPTYPES][MIGRATE_PCPTYPES - 1] = { > [MIGRATE_UNMOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE }, > [MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE }, > [MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE }, > @@ -2861,7 +2861,7 @@ int find_suitable_fallback(struct free_area *area, unsigned int order, > int i; > int fallback_mt; > > - if (area->nr_free == 0) > + if (area->nr_free == 0 || !migratetype_is_mergeable(migratetype)) > return -1; > > *can_steal = false; > @@ -2873,11 +2873,10 @@ int find_suitable_fallback(struct free_area *area, unsigned int order, > if (can_steal_fallback(order, migratetype)) > *can_steal = true; > > - if (!only_stealable) > - return fallback_mt; > - > - if (*can_steal) > + if (!only_stealable || *can_steal) > return fallback_mt; > + else > + break; > } > > return -1; > -- > 2.25.1 -- Best Regards, Yan, Zi
Attachment:
signature.asc
Description: OpenPGP digital signature
