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 <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>
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 436ce6e..80da968 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -168,6 +168,8 @@
#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 47f717f..a0e4202 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -261,6 +261,7 @@
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 @@
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 ec6dbcb9..c007e78 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1045,6 +1045,9 @@
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