[PATCH 3/5] Use per hstate nodes_allowed to constrain huge page allocation

[Lee Schermerhorn <lee.schermerhorn@hp.com>]

[PATCH 3/5] Use per hstate nodes_allowed to constrain huge page allocation

Against:  17may09 mmotm

Select only nodes from the per hstate nodes_allowed mask when
promoting surplus pages to persistent or when allocating fresh
huge pages to the pool.

Note that alloc_buddy_huge_page() still uses task policy to allocate
surplus huge pages.  This could be changed.

Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>

 mm/hugetlb.c |   23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

Index: linux-2.6.30-rc8-mmotm-090603-1633/mm/hugetlb.c
===================================================================
--- linux-2.6.30-rc8-mmotm-090603-1633.orig/mm/hugetlb.c	2009-06-04 12:59:32.000000000 -0400
+++ linux-2.6.30-rc8-mmotm-090603-1633/mm/hugetlb.c	2009-06-04 12:59:33.000000000 -0400
@@ -637,9 +637,9 @@ static struct page *alloc_fresh_huge_pag
 static int hstate_next_node(struct hstate *h)
 {
 	int next_nid;
-	next_nid = next_node(h->hugetlb_next_nid, node_online_map);
+	next_nid = next_node(h->hugetlb_next_nid, *h->nodes_allowed);
 	if (next_nid == MAX_NUMNODES)
-		next_nid = first_node(node_online_map);
+		next_nid = first_node(*h->nodes_allowed);
 	h->hugetlb_next_nid = next_nid;
 	return next_nid;
 }
@@ -652,6 +652,11 @@ static int alloc_fresh_huge_page(struct 
 	int ret = 0;
 
 	start_nid = h->hugetlb_next_nid;
+	/*
+	 * we may have allocated with a different nodes_allowed previously
+	 */
+	if (!node_isset(start_nid, *h->nodes_allowed))
+		start_nid = hstate_next_node(h);
 
 	do {
 		page = alloc_fresh_huge_page_node(h, h->hugetlb_next_nid);
@@ -1169,20 +1174,28 @@ static inline void try_to_free_low(struc
 
 /*
  * Increment or decrement surplus_huge_pages.  Keep node-specific counters
- * balanced by operating on them in a round-robin fashion.
+ * balanced by operating on them in a round-robin fashion.  Use nodes_allowed
+ * mask when decreasing suplus pages as we're "promoting" them to persistent.
+ * Use node_online_map for increment surplus pages as we're demoting previously
+ * persistent huge pages.
+ * Called holding the hugetlb_lock.
  * Returns 1 if an adjustment was made.
  */
 static int adjust_pool_surplus(struct hstate *h, int delta)
 {
+	nodemask_t *nodemask = &node_online_map;
 	static int prev_nid;
 	int nid = prev_nid;
 	int ret = 0;
 
 	VM_BUG_ON(delta != -1 && delta != 1);
+	if (delta < 0)
+		nodemask = h->nodes_allowed;
+
 	do {
-		nid = next_node(nid, node_online_map);
+		nid = next_node(nid, *nodemask);
 		if (nid == MAX_NUMNODES)
-			nid = first_node(node_online_map);
+			nid = first_node(*nodemask);
 
 		/* To shrink on this node, there must be a surplus page */
 		if (delta < 0 && !h->surplus_huge_pages_node[nid])

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>