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| author | Muchun Song <songmuchun@bytedance.com> | 2020-12-14 19:11:25 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-09-22 11:42:57 +0200 |
| commit | c88c1fd8861ea33933917b5d4ed3c1d167cb8118 (patch) | |
| tree | 87e51c26c074736df8012fbed2e463673cfc3016 /mm | |
| parent | 43b225cb64c260023bb4b7f511317c468e3259e1 (diff) | |
| download | linux-stable-c88c1fd8861ea33933917b5d4ed3c1d167cb8118.tar.gz linux-stable-c88c1fd8861ea33933917b5d4ed3c1d167cb8118.tar.bz2 linux-stable-c88c1fd8861ea33933917b5d4ed3c1d167cb8118.zip | |
mm/page_alloc: speed up the iteration of max_order
commit 7ad69832f37e3cea8557db6df7c793905f1135e8 upstream.
When we free a page whose order is very close to MAX_ORDER and greater
than pageblock_order, it wastes some CPU cycles to increase max_order to
MAX_ORDER one by one and check the pageblock migratetype of that page
repeatedly especially when MAX_ORDER is much larger than pageblock_order.
We also should not be checking migratetype of buddy when "order ==
MAX_ORDER - 1" as the buddy pfn may be invalid, so adjust the condition.
With the new check, we don't need the max_order check anymore, so we
replace it.
Also adjust max_order initialization so that it's lower by one than
previously, which makes the code hopefully more clear.
Link: https://lkml.kernel.org/r/20201204155109.55451-1-songmuchun@bytedance.com
Fixes: d9dddbf55667 ("mm/page_alloc: prevent merging between isolated and other pageblocks")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/page_alloc.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index b0c451e3b59f..babcbd8b94ea 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -814,7 +814,7 @@ static inline void __free_one_page(struct page *page, struct page *buddy; unsigned int max_order; - max_order = min_t(unsigned int, MAX_ORDER, pageblock_order + 1); + max_order = min_t(unsigned int, MAX_ORDER - 1, pageblock_order); VM_BUG_ON(!zone_is_initialized(zone)); VM_BUG_ON_PAGE(page->flags & PAGE_FLAGS_CHECK_AT_PREP, page); @@ -829,7 +829,7 @@ static inline void __free_one_page(struct page *page, VM_BUG_ON_PAGE(bad_range(zone, page), page); continue_merging: - while (order < max_order - 1) { + while (order < max_order) { buddy_idx = __find_buddy_index(page_idx, order); buddy = page + (buddy_idx - page_idx); if (!page_is_buddy(page, buddy, order)) @@ -850,7 +850,7 @@ continue_merging: page_idx = combined_idx; order++; } - if (max_order < MAX_ORDER) { + if (order < MAX_ORDER - 1) { /* If we are here, it means order is >= pageblock_order. * We want to prevent merge between freepages on isolate * pageblock and normal pageblock. Without this, pageblock @@ -871,7 +871,7 @@ continue_merging: is_migrate_isolate(buddy_mt))) goto done_merging; } - max_order++; + max_order = order + 1; goto continue_merging; } |