From 6e5029a1a9985a511649e19eab0a0656f0363489 Mon Sep 17 00:00:00 2001
From: Rik van Riel <riel@redhat.com>
Date: Thu, 7 Feb 2008 00:14:08 -0800
Subject: [PATCH] --- yaml --- r: 83775 b: refs/heads/master c:
 f1a9ee758de7de1e040de849fdef46e6802ea117 h: refs/heads/master i:   83773:
 a80e0d1e1eb1d161f562ef01fcd744ff4d4a4721   83771:
 af6f2c3e28f594847e86b87a018103ee1fb48cf3   83767:
 36763e7fbb7dce464c7d77dd5f2289086ccda768   83759:
 c3ed69b5ab607265757d92e65c28771b59a9040a   83743:
 6083148099cf8c1a2ca94349169cd8aa2bb7b838   83711:
 c95b5eb4dbc2e17e1bc0e5e48148bce1a11b82c5 v: v3

---
 [refs]            |  2 +-
 trunk/mm/vmscan.c | 27 ++++++++++++++++++++++-----
 2 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/[refs] b/[refs]
index 50a444e69233..f8c1a092d570 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: fef1bdd68c81b71882ccb6f47c70980a03182063
+refs/heads/master: f1a9ee758de7de1e040de849fdef46e6802ea117
diff --git a/trunk/mm/vmscan.c b/trunk/mm/vmscan.c
index b7d868cbca09..1b85217b528c 100644
--- a/trunk/mm/vmscan.c
+++ b/trunk/mm/vmscan.c
@@ -70,6 +70,13 @@ struct scan_control {
 
 	int order;
 
+	/*
+	 * Pages that have (or should have) IO pending.  If we run into
+	 * a lot of these, we're better off waiting a little for IO to
+	 * finish rather than scanning more pages in the VM.
+	 */
+	int nr_io_pages;
+
 	/* Which cgroup do we reclaim from */
 	struct mem_cgroup *mem_cgroup;
 
@@ -499,8 +506,10 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 			 */
 			if (sync_writeback == PAGEOUT_IO_SYNC && may_enter_fs)
 				wait_on_page_writeback(page);
-			else
+			else {
+				sc->nr_io_pages++;
 				goto keep_locked;
+			}
 		}
 
 		referenced = page_referenced(page, 1, sc->mem_cgroup);
@@ -539,8 +548,10 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 		if (PageDirty(page)) {
 			if (sc->order <= PAGE_ALLOC_COSTLY_ORDER && referenced)
 				goto keep_locked;
-			if (!may_enter_fs)
+			if (!may_enter_fs) {
+				sc->nr_io_pages++;
 				goto keep_locked;
+			}
 			if (!sc->may_writepage)
 				goto keep_locked;
 
@@ -551,8 +562,10 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 			case PAGE_ACTIVATE:
 				goto activate_locked;
 			case PAGE_SUCCESS:
-				if (PageWriteback(page) || PageDirty(page))
+				if (PageWriteback(page) || PageDirty(page)) {
+					sc->nr_io_pages++;
 					goto keep;
+				}
 				/*
 				 * A synchronous write - probably a ramdisk.  Go
 				 * ahead and try to reclaim the page.
@@ -1259,6 +1272,7 @@ static unsigned long do_try_to_free_pages(struct zone **zones, gfp_t gfp_mask,
 
 	for (priority = DEF_PRIORITY; priority >= 0; priority--) {
 		sc->nr_scanned = 0;
+		sc->nr_io_pages = 0;
 		if (!priority)
 			disable_swap_token();
 		nr_reclaimed += shrink_zones(priority, zones, sc);
@@ -1292,7 +1306,8 @@ static unsigned long do_try_to_free_pages(struct zone **zones, gfp_t gfp_mask,
 		}
 
 		/* Take a nap, wait for some writeback to complete */
-		if (sc->nr_scanned && priority < DEF_PRIORITY - 2)
+		if (sc->nr_scanned && priority < DEF_PRIORITY - 2 &&
+				sc->nr_io_pages > sc->swap_cluster_max)
 			congestion_wait(WRITE, HZ/10);
 	}
 	/* top priority shrink_caches still had more to do? don't OOM, then */
@@ -1424,6 +1439,7 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order)
 		if (!priority)
 			disable_swap_token();
 
+		sc.nr_io_pages = 0;
 		all_zones_ok = 1;
 
 		/*
@@ -1516,7 +1532,8 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order)
 		 * OK, kswapd is getting into trouble.  Take a nap, then take
 		 * another pass across the zones.
 		 */
-		if (total_scanned && priority < DEF_PRIORITY - 2)
+		if (total_scanned && priority < DEF_PRIORITY - 2 &&
+					sc.nr_io_pages > sc.swap_cluster_max)
 			congestion_wait(WRITE, HZ/10);
 
 		/*