From 3c7ccfde13a9042f227a03f3873181573973c235 Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Thu, 25 Aug 2011 09:46:44 +1000 Subject: [PATCH] In async mode, compaction doesn't migrate dirty or writeback pages. So, it's meaningless to pick the page and re-add it to lru list. Of course, when we isolate the page in compaction, the page might be dirty or writeback but when we try to migrate the page, the page would be not dirty, writeback. So it could be migrated. But it's very unlikely as isolate and migration cycle is much faster than writeout. So, this patch helps cpu overhead and prevent unnecessary LRU churning. Signed-off-by: Minchan Kim Acked-by: Johannes Weiner Reviewed-by: KAMEZAWA Hiroyuki Reviewed-by: KOSAKI Motohiro Acked-by: Mel Gorman Acked-by: Rik van Riel Reviewed-by: Michal Hocko Cc: Andrea Arcangeli Signed-off-by: Andrew Morton --- include/linux/mmzone.h | 3 ++- mm/compaction.c | 7 +++++-- mm/vmscan.c | 3 +++ 3 files changed, 10 insertions(+), 3 deletions(-) diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 4bf3b1eed05a..ad4b490b926c 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -168,7 +168,8 @@ static inline int is_unevictable_lru(enum lru_list l) #define ISOLATE_INACTIVE ((__force fmode_t)0x1) /* Isolate active pages */ #define ISOLATE_ACTIVE ((__force fmode_t)0x2) - +/* Isolate clean file */ +#define ISOLATE_CLEAN ((__force fmode_t)0x4) /* LRU Isolation modes. */ typedef unsigned __bitwise__ isolate_mode_t; diff --git a/mm/compaction.c b/mm/compaction.c index 47f717fa4233..a0e420207ebf 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -261,6 +261,7 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone, unsigned long last_pageblock_nr = 0, pageblock_nr; unsigned long nr_scanned = 0, nr_isolated = 0; struct list_head *migratelist = &cc->migratepages; + isolate_mode_t mode = ISOLATE_ACTIVE|ISOLATE_INACTIVE; /* Do not scan outside zone boundaries */ low_pfn = max(cc->migrate_pfn, zone->zone_start_pfn); @@ -348,9 +349,11 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone, continue; } + if (!cc->sync) + mode |= ISOLATE_CLEAN; + /* Try isolate the page */ - if (__isolate_lru_page(page, - ISOLATE_ACTIVE|ISOLATE_INACTIVE, 0) != 0) + if (__isolate_lru_page(page, mode, 0) != 0) continue; VM_BUG_ON(PageTransCompound(page)); diff --git a/mm/vmscan.c b/mm/vmscan.c index 24054a991d5c..536b45ddc4c6 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1046,6 +1046,9 @@ int __isolate_lru_page(struct page *page, isolate_mode_t mode, int file) ret = -EBUSY; + if ((mode & ISOLATE_CLEAN) && (PageDirty(page) || PageWriteback(page))) + return ret; + if (likely(get_page_unless_zero(page))) { /* * Be careful not to clear PageLRU until after we're -- 2.39.5