[RFC][ for -mm] memory controller enhancements for NUMA [8/10] move reclaim_mapped calc routine (cleanup for later patch)

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

Just for clean up for later patch for avoiding dirty nesting....

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

 mm/vmscan.c |  184 +++++++++++++++++++++++++++++++-----------------------------
 1 file changed, 97 insertions(+), 87 deletions(-)

Index: linux-2.6.24-rc2-mm1/mm/vmscan.c
===================================================================
--- linux-2.6.24-rc2-mm1.orig/mm/vmscan.c
+++ linux-2.6.24-rc2-mm1/mm/vmscan.c
@@ -950,6 +950,98 @@ static inline int zone_is_near_oom(struc
 }
 
 /*
+ * Determine we should try to reclaim mapped pages.
+ */
+static int calc_reclaim_mapped(struct zone *zone, int priority, int swappiness)
+{
+	long mapped_ratio;
+	long distress;
+	long swap_tendency;
+	long imbalance;
+	int reclaim_mapped;
+
+	if (zone_is_near_oom(zone))
+		return 1;
+	/*
+	 * `distress' is a measure of how much trouble we're having
+	 * reclaiming pages.  0 -> no problems.  100 -> great trouble.
+	 */
+	distress = 100 >> min(zone->prev_priority, priority);
+
+	/*
+	 * The point of this algorithm is to decide when to start
+	 * reclaiming mapped memory instead of just pagecache.  Work out
+	 * how much memory
+	 * is mapped.
+	 */
+	mapped_ratio = ((global_page_state(NR_FILE_MAPPED) +
+			global_page_state(NR_ANON_PAGES)) * 100) /
+				vm_total_pages;
+	/*
+	 * Now decide how much we really want to unmap some pages.  The
+	 * mapped ratio is downgraded - just because there's a lot of
+	 * mapped memory doesn't necessarily mean that page reclaim
+	 * isn't succeeding.
+	 *
+	 * The distress ratio is important - we don't want to start
+	 * going oom.
+	 *
+	 * A 100% value of vm_swappiness overrides this algorithm
+	 * altogether.
+	 */
+	swap_tendency = mapped_ratio / 2 + distress + swappiness;
+
+	/*
+	 * If there's huge imbalance between active and inactive
+	 * (think active 100 times larger than inactive) we should
+	 * become more permissive, or the system will take too much
+	 * cpu before it start swapping during memory pressure.
+	 * Distress is about avoiding early-oom, this is about
+	 * making swappiness graceful despite setting it to low
+	 * values.
+	 *
+	 * Avoid div by zero with nr_inactive+1, and max resulting
+	 * value is vm_total_pages.
+	 */
+	imbalance  = zone_page_state(zone, NR_ACTIVE);
+	imbalance /= zone_page_state(zone, NR_INACTIVE) + 1;
+
+	/*
+	 * Reduce the effect of imbalance if swappiness is low,
+	 * this means for a swappiness very low, the imbalance
+	 * must be much higher than 100 for this logic to make
+	 * the difference.
+	 *
+	 * Max temporary value is vm_total_pages*100.
+	 */
+	imbalance *= (vm_swappiness + 1);
+	imbalance /= 100;
+
+	/*
+	 * If not much of the ram is mapped, makes the imbalance
+	 * less relevant, it's high priority we refill the inactive
+	 * list with mapped pages only in presence of high ratio of
+	 * mapped pages.
+	 *
+	 * Max temporary value is vm_total_pages*100.
+	 */
+	imbalance *= mapped_ratio;
+	imbalance /= 100;
+
+	/* apply imbalance feedback to swap_tendency */
+	swap_tendency += imbalance;
+
+	/*
+	 * Now use this metric to decide whether to start moving mapped
+	 * memory onto the inactive list.
+	 */
+	if (swap_tendency >= 100)
+		reclaim_mapped = 1;
+
+	return reclaim_mapped;
+}
+
+/*
  * This moves pages from the active list to the inactive list.
  *
  * We move them the other way if the page is referenced by one or more
@@ -966,6 +1058,8 @@ static inline int zone_is_near_oom(struc
  * The downside is that we have to touch page->_count against each page.
  * But we had to alter page->flags anyway.
  */
+
+
 static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
 				struct scan_control *sc, int priority)
 {
@@ -979,93 +1073,9 @@ static void shrink_active_list(unsigned 
 	struct pagevec pvec;
 	int reclaim_mapped = 0;
 
-	if (sc->may_swap) {
-		long mapped_ratio;
-		long distress;
-		long swap_tendency;
-		long imbalance;
-
-		if (zone_is_near_oom(zone))
-			goto force_reclaim_mapped;
-
-		/*
-		 * `distress' is a measure of how much trouble we're having
-		 * reclaiming pages.  0 -> no problems.  100 -> great trouble.
-		 */
-		distress = 100 >> min(zone->prev_priority, priority);
-
-		/*
-		 * The point of this algorithm is to decide when to start
-		 * reclaiming mapped memory instead of just pagecache.  Work out
-		 * how much memory
-		 * is mapped.
-		 */
-		mapped_ratio = ((global_page_state(NR_FILE_MAPPED) +
-				global_page_state(NR_ANON_PAGES)) * 100) /
-					vm_total_pages;
-
-		/*
-		 * Now decide how much we really want to unmap some pages.  The
-		 * mapped ratio is downgraded - just because there's a lot of
-		 * mapped memory doesn't necessarily mean that page reclaim
-		 * isn't succeeding.
-		 *
-		 * The distress ratio is important - we don't want to start
-		 * going oom.
-		 *
-		 * A 100% value of vm_swappiness overrides this algorithm
-		 * altogether.
-		 */
-		swap_tendency = mapped_ratio / 2 + distress + sc->swappiness;
-
-		/*
-		 * If there's huge imbalance between active and inactive
-		 * (think active 100 times larger than inactive) we should
-		 * become more permissive, or the system will take too much
-		 * cpu before it start swapping during memory pressure.
-		 * Distress is about avoiding early-oom, this is about
-		 * making swappiness graceful despite setting it to low
-		 * values.
-		 *
-		 * Avoid div by zero with nr_inactive+1, and max resulting
-		 * value is vm_total_pages.
-		 */
-		imbalance  = zone_page_state(zone, NR_ACTIVE);
-		imbalance /= zone_page_state(zone, NR_INACTIVE) + 1;
-
-		/*
-		 * Reduce the effect of imbalance if swappiness is low,
-		 * this means for a swappiness very low, the imbalance
-		 * must be much higher than 100 for this logic to make
-		 * the difference.
-		 *
-		 * Max temporary value is vm_total_pages*100.
-		 */
-		imbalance *= (vm_swappiness + 1);
-		imbalance /= 100;
-
-		/*
-		 * If not much of the ram is mapped, makes the imbalance
-		 * less relevant, it's high priority we refill the inactive
-		 * list with mapped pages only in presence of high ratio of
-		 * mapped pages.
-		 *
-		 * Max temporary value is vm_total_pages*100.
-		 */
-		imbalance *= mapped_ratio;
-		imbalance /= 100;
-
-		/* apply imbalance feedback to swap_tendency */
-		swap_tendency += imbalance;
-
-		/*
-		 * Now use this metric to decide whether to start moving mapped
-		 * memory onto the inactive list.
-		 */
-		if (swap_tendency >= 100)
-force_reclaim_mapped:
-			reclaim_mapped = 1;
-	}
+	if (sc->may_swap)
+		reclaim_mapped = calc_reclaim_mapped(zone, priority,
+						     sc->swappiness);
 
 	lru_add_drain();
 	spin_lock_irq(&zone->lru_lock);

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