mm: compaction: make isolate_lru_page() filter-aware (39deaf85) · Commits · 戴 / test

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 <minchan.kim@gmail.com> Acked-by:

Johannes Weiner <hannes@cmpxchg.org> Reviewed-by:

KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by:

KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by:

Mel Gorman <mgorman@suse.de> Acked-by:

Rik van Riel <riel@redhat.com> Reviewed-by:

Michal Hocko <mhocko@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

include/linux/mmzone.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -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;

mm/compaction.c

+5 −2

Original line number	Diff line number	Diff line
		@@ -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));

mm/vmscan.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -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

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