From 39deaf8585152f1a35c1676d3d7dc6ae0fb65967 Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Mon, 31 Oct 2011 17:06:51 -0700 Subject: [PATCH] mm: compaction: make isolate_lru_page() filter-aware 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 Signed-off-by: Linus Torvalds --- include/linux/mmzone.h | 2 ++ mm/compaction.c | 7 +++++-- mm/vmscan.c | 3 +++ 3 files changed, 10 insertions(+), 2 deletions(-) diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 436ce6e7a44..80da968798e 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -168,6 +168,8 @@ static inline int is_unevictable_lru(enum lru_list l) #define ISOLATE_INACTIVE ((__force isolate_mode_t)0x1) /* Isolate active pages */ #define ISOLATE_ACTIVE ((__force isolate_mode_t)0x2) +/* Isolate clean file */ +#define ISOLATE_CLEAN ((__force isolate_mode_t)0x4) /* LRU Isolation modes. */ typedef unsigned __bitwise__ isolate_mode_t; diff --git a/mm/compaction.c b/mm/compaction.c index 47f717fa423..a0e420207eb 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 ec6dbcb976d..c007e78d707 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1045,6 +1045,9 @@ 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 -- 2.20.1