[PATCH 03/10] mm: mempolicy: promote page to DRAM for MPOL_HYBRID

[Yang Shi]

With MPOL_HYBRID the memory allocation may end up on non-DRAM node, this
may be not optimal for performance.  Promote pages to DRAM with NUMA
balancing for MPOL_HYBRID.

If DRAM nodes are specified, migrate to the specified nodes.  If no DRAM
node is specified, migrate to the local DRAM node.

Signed-off-by: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
---
 mm/mempolicy.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 7d0a432..87bc691 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -2339,6 +2339,7 @@ int mpol_misplaced(struct page *page, struct vm_area_struct *vma, unsigned long
 	struct zoneref *z;
 	int curnid = page_to_nid(page);
 	unsigned long pgoff;
+	nodemask_t nmask;
 	int thiscpu = raw_smp_processor_id();
 	int thisnid = cpu_to_node(thiscpu);
 	int polnid = NUMA_NO_NODE;
@@ -2363,7 +2364,24 @@ int mpol_misplaced(struct page *page, struct vm_area_struct *vma, unsigned long
 		break;
 
 	case MPOL_HYBRID:
-		/* Fall through */
+		if (node_isset(curnid, pol->v.nodes) &&
+		    node_isset(curnid, def_alloc_nodemask))
+			/* The page is already on DRAM node */
+			goto out;
+
+		/*
+		 * Promote to the DRAM node specified by the policy, or
+		 * the local DRAM node if no DRAM node is specified.
+		 */
+		nodes_and(nmask, pol->v.nodes, def_alloc_nodemask);
+
+		z = first_zones_zonelist(
+			node_zonelist(numa_node_id(), GFP_HIGHUSER),
+			gfp_zone(GFP_HIGHUSER),
+			nodes_empty(nmask) ? &def_alloc_nodemask : &nmask);
+		polnid = z->zone->node;
+
+		break;
 
 	case MPOL_BIND:
 
-- 
1.8.3.1