linux-kernel - [PATCH 3/5] mm, compaction: encapsulate resetting cached scanner positions

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Date:	Mon, 19 Jan 2015 11:05:18 +0100
From:	Vlastimil Babka <vbabka@...e.cz>
To:	linux-mm@...ck.org
Cc:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Vlastimil Babka <vbabka@...e.cz>,
	Minchan Kim <minchan@...nel.org>, Mel Gorman <mgorman@...e.de>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Michal Nazarewicz <mina86@...a86.com>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	Christoph Lameter <cl@...ux.com>,
	Rik van Riel <riel@...hat.com>,
	David Rientjes <rientjes@...gle.com>
Subject: [PATCH 3/5] mm, compaction: encapsulate resetting cached scanner positions

Reseting the cached compaction scanner positions is now done implicitly in
__reset_isolation_suitable() and compact_finished(). Encapsulate the
functionality in a new function reset_cached_positions() and call it
explicitly where needed.

Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
Cc: Minchan Kim <minchan@...nel.org>
Cc: Mel Gorman <mgorman@...e.de>
Cc: Joonsoo Kim <iamjoonsoo.kim@....com>
Cc: Michal Nazarewicz <mina86@...a86.com>
Cc: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Cc: Christoph Lameter <cl@...ux.com>
Cc: Rik van Riel <riel@...hat.com>
Cc: David Rientjes <rientjes@...gle.com>
---
 mm/compaction.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/mm/compaction.c b/mm/compaction.c
index 45799a4..5626220 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -123,6 +123,13 @@ static inline bool isolation_suitable(struct compact_control *cc,
 	return !get_pageblock_skip(page);
 }
 
+static void reset_cached_positions(struct zone *zone)
+{
+	zone->compact_cached_migrate_pfn[0] = zone->zone_start_pfn;
+	zone->compact_cached_migrate_pfn[1] = zone->zone_start_pfn;
+	zone->compact_cached_free_pfn = zone_end_pfn(zone);
+}
+
 /*
  * This function is called to clear all cached information on pageblocks that
  * should be skipped for page isolation when the migrate and free page scanner
@@ -134,9 +141,6 @@ static void __reset_isolation_suitable(struct zone *zone)
 	unsigned long end_pfn = zone_end_pfn(zone);
 	unsigned long pfn;
 
-	zone->compact_cached_migrate_pfn[0] = start_pfn;
-	zone->compact_cached_migrate_pfn[1] = start_pfn;
-	zone->compact_cached_free_pfn = end_pfn;
 	zone->compact_blockskip_flush = false;
 
 	/* Walk the zone and mark every pageblock as suitable for isolation */
@@ -166,8 +170,10 @@ void reset_isolation_suitable(pg_data_t *pgdat)
 			continue;
 
 		/* Only flush if a full compaction finished recently */
-		if (zone->compact_blockskip_flush)
+		if (zone->compact_blockskip_flush) {
 			__reset_isolation_suitable(zone);
+			reset_cached_positions(zone);
+		}
 	}
 }
 
@@ -1059,9 +1065,7 @@ static int compact_finished(struct zone *zone, struct compact_control *cc,
 	/* Compaction run completes if the migrate and free scanner meet */
 	if (compact_scanners_met(cc)) {
 		/* Let the next compaction start anew. */
-		zone->compact_cached_migrate_pfn[0] = zone->zone_start_pfn;
-		zone->compact_cached_migrate_pfn[1] = zone->zone_start_pfn;
-		zone->compact_cached_free_pfn = zone_end_pfn(zone);
+		reset_cached_positions(zone);
 
 		/*
 		 * Mark that the PG_migrate_skip information should be cleared
@@ -1187,8 +1191,10 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
 	 * is about to be retried after being deferred. kswapd does not do
 	 * this reset as it'll reset the cached information when going to sleep.
 	 */
-	if (compaction_restarting(zone, cc->order) && !current_is_kswapd())
+	if (compaction_restarting(zone, cc->order) && !current_is_kswapd()) {
 		__reset_isolation_suitable(zone);
+		reset_cached_positions(zone);
+	}
 
 	/*
 	 * Setup to move all movable pages to the end of the zone. Used cached
-- 
2.1.2

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