[RFC 5/7] Laundry handling for direct reclaim

[Christoph Lameter <clameter@sgi.com>]

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Direct reclaim collects a global laundry list in try_to_free_pages().

Pages are only written back after a reclaim pass is complete.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

---
 mm/vmscan.c |   12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

Index: linux-2.6/mm/vmscan.c
===================================================================
--- linux-2.6.orig/mm/vmscan.c	2007-08-19 23:30:15.000000000 -0700
+++ linux-2.6/mm/vmscan.c	2007-08-19 23:53:43.000000000 -0700
@@ -1099,7 +1099,7 @@ static unsigned long shrink_zone(int pri
  * scan then give up on it.
  */
 static unsigned long shrink_zones(int priority, struct zone **zones,
-					struct scan_control *sc)
+			struct scan_control *sc, struct list_head *laundry)
 {
 	unsigned long nr_reclaimed = 0;
 	int i;
@@ -1121,7 +1121,7 @@ static unsigned long shrink_zones(int pr
 
 		sc->all_unreclaimable = 0;
 
-		nr_reclaimed += shrink_zone(priority, zone, sc, NULL);
+		nr_reclaimed += shrink_zone(priority, zone, sc, laundry);
 	}
 	return nr_reclaimed;
 }
@@ -1156,6 +1156,7 @@ unsigned long try_to_free_pages(struct z
 		.swappiness = vm_swappiness,
 		.order = order,
 	};
+	LIST_HEAD(laundry);
 
 	count_vm_event(ALLOCSTALL);
 
@@ -1170,16 +1171,19 @@ unsigned long try_to_free_pages(struct z
 	}
 
 	for (priority = DEF_PRIORITY; priority >= 0; priority--) {
+
 		sc.nr_scanned = 0;
 		if (!priority)
 			disable_swap_token();
-		nr_reclaimed += shrink_zones(priority, zones, &sc);
+		nr_reclaimed += shrink_zones(priority, zones, &sc, &laundry);
 		shrink_slab(sc.nr_scanned, gfp_mask, lru_pages);
 		if (reclaim_state) {
 			nr_reclaimed += reclaim_state->reclaimed_slab;
 			reclaim_state->reclaimed_slab = 0;
 		}
+
 		total_scanned += sc.nr_scanned;
+
 		if (nr_reclaimed >= sc.swap_cluster_max) {
 			ret = 1;
 			goto out;
@@ -1223,6 +1227,8 @@ out:
 
 		zone->prev_priority = priority;
 	}
+	nr_reclaimed += shrink_page_list(&laundry, &sc, NULL);
+	release_lru_pages(&laundry);
 	return ret;
 }
 

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