[PATCH] change global zonelist order v4 [1/2] change zonelist ordering.

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

Make zonelist creation policy selectable from sysctl v4.
Automatic configuration itself is provided by the next patch.

[Description]
Assume 2 node NUMA, only node(0) has ZONE_DMA.
(ia64's ZONE_DMA is below 4GB...x86_64's ZONE_DMA32)

In this case, current default (node0's) zonelist order is

Node(0)'s NORMAL -> Node(0)'s DMA -> Node(1)"s NORMAL.

This means Node(0)'s DMA will be used before Node(1)'s NORMAL.

This patch changes *default* zone order to

Node(0)'s NORMAL -> Node(1)'s NORMAL -> Node(0)'s DMA.

But, if Node(0)'s memory is too small (near or below 4G), Node(0)'s process has
to allocate its memory from Node(1) even if there are free memory in Node(0).
Some applications/uses will dislike this.
This patch adds a knob to change zonelist ordering.

[What this patch adds]

command:
%echo N > /proc/sys/vm/numa_zonelist_order

Will rebuild zonelist in following order(old style, NODE order).

Node(0)'s NORMAL -> Node(0)'s DMA -> Node(0)'s NORMAL.

means put more priority on locality.

command:
%echo Z > /proc/sys/vm/numa_zonelist_order

Will rebuild zonelist in following order(new style, ZONE order)

Node(0)'s NORMAL -> Node(1)'s NORMAL -> Node(0)'s DMA.

means put more priority on zone_type.

And you can specify this option as boot param.

Because autoconfig function does nothing. Default is "Node" order.

Tested on ia64 2-Node NUMA. works well.

Signed-Off-By: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

---
 Documentation/kernel-parameters.txt |   10 +
 Documentation/sysctl/vm.txt         |   32 ++++++
 include/linux/mmzone.h              |    5 
 kernel/sysctl.c                     |    9 +
 mm/page_alloc.c                     |  185 ++++++++++++++++++++++++++++++++----
 5 files changed, 225 insertions(+), 16 deletions(-)

Index: linux-2.6.21-rc7-mm2/kernel/sysctl.c
===================================================================
--- linux-2.6.21-rc7-mm2.orig/kernel/sysctl.c
+++ linux-2.6.21-rc7-mm2/kernel/sysctl.c
@@ -893,6 +893,15 @@ static ctl_table vm_table[] = {
 		.extra1		= &zero,
 		.extra2		= &one_hundred,
 	},
+	{
+		.ctl_name	= CTL_UNNUMBERED,
+		.procname	= "numa_zonelist_order",
+		.data		= &numa_zonelist_order,
+		.maxlen		= NUMA_ZONELIST_ORDER_LEN,
+		.mode		= 0644,
+		.proc_handler	= &numa_zonelist_order_handler,
+		.strategy	= &sysctl_string,
+	},
 #endif
 #if defined(CONFIG_X86_32) || \
    (defined(CONFIG_SUPERH) && defined(CONFIG_VSYSCALL))
Index: linux-2.6.21-rc7-mm2/mm/page_alloc.c
===================================================================
--- linux-2.6.21-rc7-mm2.orig/mm/page_alloc.c
+++ linux-2.6.21-rc7-mm2/mm/page_alloc.c
@@ -2024,7 +2024,8 @@ void show_free_areas(void)
  * Add all populated zones of a node to the zonelist.
  */
 static int __meminit build_zonelists_node(pg_data_t *pgdat,
-			struct zonelist *zonelist, int nr_zones, enum zone_type zone_type)
+			struct zonelist *zonelist, int nr_zones,
+			enum zone_type zone_type)
 {
 	struct zone *zone;
 
@@ -2045,7 +2046,7 @@ static int __meminit build_zonelists_nod
 
 #ifdef CONFIG_NUMA
 #define MAX_NODE_LOAD (num_online_nodes())
-static int __meminitdata node_load[MAX_NUMNODES];
+static int node_load[MAX_NUMNODES];
 /**
  * find_next_best_node - find the next node that should appear in a given node's fallback list
  * @node: node whose fallback list we're appending
@@ -2060,7 +2061,7 @@ static int __meminitdata node_load[MAX_N
  * on them otherwise.
  * It returns -1 if no node is found.
  */
-static int __meminit find_next_best_node(int node, nodemask_t *used_node_mask)
+static int find_next_best_node(int node, nodemask_t *used_node_mask)
 {
 	int n, val;
 	int min_val = INT_MAX;
@@ -2106,13 +2107,124 @@ static int __meminit find_next_best_node
 	return best_node;
 }
 
-static void __meminit build_zonelists(pg_data_t *pgdat)
+/*
+ * numa_zonelist_order:
+ *  0 = automatic detection of better ordering.
+ *  1 = order by ([node] distance, -zonetype)
+ *  2 = order by (-zonetype, [node] distance)
+ */
+#define ZONELIST_ORDER_AUTO	0
+#define ZONELIST_ORDER_NODE	1
+#define ZONELIST_ORDER_ZONE	2
+static int zonelist_order = 0;
+
+/*
+ * command line option "numa_zonelist_order"
+ *	= "[dD]efault | "0"	- default, automatic configuration.
+ *	= "[nN]ode"|"1" 	- order by node locality,
+ *         			  then zone within node.
+ *	= "[zZ]one"|"2" - order by zone, then by locality within zone
+ */
+char numa_zonelist_order[NUMA_ZONELIST_ORDER_LEN] = "default";
+
+static int __parse_numa_zonelist_order(char *s)
+{
+	if (*s == 'd' || *s == 'D' || *s == '0') {
+		strncpy(numa_zonelist_order, "default",
+					NUMA_ZONELIST_ORDER_LEN);
+		zonelist_order = ZONELIST_ORDER_AUTO;
+	} else if (*s == 'n' || *s == 'N' || *s == '1') {
+		strncpy(numa_zonelist_order, "node",
+					NUMA_ZONELIST_ORDER_LEN);
+		zonelist_order = ZONELIST_ORDER_NODE;
+	} else if (*s == 'z' || *s == 'Z' || *s == '2') {
+		strncpy(numa_zonelist_order, "zone",
+					NUMA_ZONELIST_ORDER_LEN);
+		zonelist_order = ZONELIST_ORDER_ZONE;
+	} else {
+		printk(KERN_WARNING
+			"Ignoring invalid numa_zonelist_order value:  "
+			"%s\n", s);
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static __init int setup_numa_zonelist_order(char *s)
+{
+	if (s)
+		return __parse_numa_zonelist_order(s);
+	return 0;
+}
+early_param("numa_zonelist_order", setup_numa_zonelist_order);
+
+/*
+ * Build zonelists ordered by node and zones within node.
+ * This results in maximum locality--normal zone overflows into local
+ * DMA zone, if any--but risks exhausting DMA zone.
+ */
+static void build_zonelists_in_node_order(pg_data_t *pgdat, int node)
 {
-	int j, node, local_node;
 	enum zone_type i;
-	int prev_node, load;
+	int j;
+	struct zonelist *zonelist;
+
+	for (i = 0; i < MAX_NR_ZONES; i++) {
+		zonelist = pgdat->node_zonelists + i;
+		for (j = 0; zonelist->zones[j] != NULL; j++);
+
+ 		j = build_zonelists_node(NODE_DATA(node), zonelist, j, i);
+		zonelist->zones[j] = NULL;
+	}
+}
+
+/*
+ * Build zonelists ordered by zone and nodes within zones.
+ * This results in conserving DMA zone[s] until all Normal memory is
+ * exhausted, but results in overflowing to remote node while memory
+ * may still exist in local DMA zone.
+ */
+static int node_order[MAX_NUMNODES];
+
+static void build_zonelists_in_zone_order(pg_data_t *pgdat, int nr_nodes)
+{
+	enum zone_type i;
+	int pos, j, node;
+	int zone_type;		/* needs to be signed */
+	struct zone *z;
 	struct zonelist *zonelist;
+
+	for (i = 0; i < MAX_NR_ZONES; i++) {
+		zonelist = pgdat->node_zonelists + i;
+		pos = 0;
+		for (zone_type = i; zone_type >= 0; zone_type--) {
+			for (j = 0; j < nr_nodes; j++) {
+				node = node_order[j];
+				z = &NODE_DATA(node)->node_zones[zone_type];
+				if (populated_zone(z))
+					zonelist->zones[pos++] = z;
+			}
+		}
+		zonelist->zones[pos] = NULL;
+	}
+}
+
+static int estimate_zonelist_order(void)
+{
+	/* dummy, just select node order. */
+	return ZONELIST_ORDER_NODE;
+}
+
+
+
+static void build_zonelists(pg_data_t *pgdat)
+{
+	int j, node, load;
+	enum zone_type i;
 	nodemask_t used_mask;
+	int local_node, prev_node;
+	struct zonelist *zonelist;
+	int ordering;
 
 	/* initialize zonelists */
 	for (i = 0; i < MAX_NR_ZONES; i++) {
@@ -2120,11 +2232,18 @@ static void __meminit build_zonelists(pg
 		zonelist->zones[0] = NULL;
 	}
 
+	ordering = zonelist_order;
+	if (ordering == ZONELIST_ORDER_AUTO)
+		ordering = estimate_zonelist_order();
 	/* NUMA-aware ordering of nodes */
 	local_node = pgdat->node_id;
 	load = num_online_nodes();
 	prev_node = local_node;
 	nodes_clear(used_mask);
+
+	memset(node_order, 0, sizeof(node_order));
+	j = 0;
+
 	while ((node = find_next_best_node(local_node, &used_mask)) >= 0) {
 		int distance = node_distance(local_node, node);
 
@@ -2140,18 +2259,20 @@ static void __meminit build_zonelists(pg
 		 * So adding penalty to the first node in same
 		 * distance group to make it round-robin.
 		 */
-
 		if (distance != node_distance(local_node, prev_node))
-			node_load[node] += load;
+			node_load[node] = load;
+
 		prev_node = node;
 		load--;
-		for (i = 0; i < MAX_NR_ZONES; i++) {
-			zonelist = pgdat->node_zonelists + i;
-			for (j = 0; zonelist->zones[j] != NULL; j++);
+		if (ordering == ZONELIST_ORDER_NODE)	/* default */
+			build_zonelists_in_node_order(pgdat, node);
+		else
+			node_order[j++] = node;	/* remember order */
+	}
 
-	 		j = build_zonelists_node(NODE_DATA(node), zonelist, j, i);
-			zonelist->zones[j] = NULL;
-		}
+	if (ordering == ZONELIST_ORDER_ZONE) {
+		/* calculate node order -- i.e., DMA last! */
+		build_zonelists_in_zone_order(pgdat, j);
 	}
 }
 
@@ -2173,6 +2294,37 @@ static void __meminit build_zonelist_cac
 	}
 }
 
+/*
+ * sysctl handler for numa_zonelist_order
+ */
+int numa_zonelist_order_handler(ctl_table *table, int write,
+		struct file *file, void __user *buffer, size_t *length,
+		loff_t *ppos)
+{
+	char saved_string[NUMA_ZONELIST_ORDER_LEN];
+	int ret;
+
+	if (write)
+		strncpy(saved_string, (char*)table->data,
+			NUMA_ZONELIST_ORDER_LEN);
+	ret = proc_dostring(table, write, file, buffer, length, ppos);
+	if (ret)
+		return ret;
+	if (write) {
+		int oldval = zonelist_order;
+		if (__parse_numa_zonelist_order((char*)table->data)) {
+			/*
+			 * bogus value.  restore saved string
+			 */
+			strncpy((char*)table->data, saved_string,
+				NUMA_ZONELIST_ORDER_LEN);
+			zonelist_order = oldval;
+		} else if (oldval != zonelist_order)
+			build_all_zonelists();
+	}
+	return 0;
+}
+
 #else	/* CONFIG_NUMA */
 
 static void __meminit build_zonelists(pg_data_t *pgdat)
@@ -2222,7 +2374,7 @@ static void __meminit build_zonelist_cac
 #endif	/* CONFIG_NUMA */
 
 /* return values int ....just for stop_machine_run() */
-static int __meminit __build_all_zonelists(void *dummy)
+static int __build_all_zonelists(void *dummy)
 {
 	int nid;
 
@@ -2233,12 +2385,13 @@ static int __meminit __build_all_zonelis
 	return 0;
 }
 
-void __meminit build_all_zonelists(void)
+void build_all_zonelists(void)
 {
 	if (system_state == SYSTEM_BOOTING) {
 		__build_all_zonelists(NULL);
 		cpuset_init_current_mems_allowed();
 	} else {
+		memset(node_load, 0, sizeof(node_load));
 		/* we have to stop all cpus to guaranntee there is no user
 		   of zonelist */
 		stop_machine_run(__build_all_zonelists, NULL, NR_CPUS);
Index: linux-2.6.21-rc7-mm2/include/linux/mmzone.h
===================================================================
--- linux-2.6.21-rc7-mm2.orig/include/linux/mmzone.h
+++ linux-2.6.21-rc7-mm2/include/linux/mmzone.h
@@ -608,6 +608,11 @@ int sysctl_min_unmapped_ratio_sysctl_han
 int sysctl_min_slab_ratio_sysctl_handler(struct ctl_table *, int,
 			struct file *, void __user *, size_t *, loff_t *);
 
+extern int numa_zonelist_order_handler(struct ctl_table *, int,
+			struct file *, void __user *, size_t *, loff_t *);
+extern char numa_zonelist_order[];
+#define NUMA_ZONELIST_ORDER_LEN 16	/* string buffer size */
+
 #include <linux/topology.h>
 /* Returns the number of the current Node. */
 #ifndef numa_node_id
Index: linux-2.6.21-rc7-mm2/Documentation/kernel-parameters.txt
===================================================================
--- linux-2.6.21-rc7-mm2.orig/Documentation/kernel-parameters.txt
+++ linux-2.6.21-rc7-mm2/Documentation/kernel-parameters.txt
@@ -1500,6 +1500,16 @@ and is between 256 and 4096 characters. 
 			Format: <reboot_mode>[,<reboot_mode2>[,...]]
 			See arch/*/kernel/reboot.c or arch/*/kernel/process.c			
 
+	numa_zonelist_order [KNL,BOOT]
+			Select memory allocation zonelist order for NUMA
+			platform.  Default is automatic configuration.
+			"Node order" orders the zonelists by node [locality],
+			then zones within nodes.  "Zone order" orders the
+			zonelists by zone,then nodes within the zone.
+			This moves DMA zone, if any, to the end of the
+			allocation lists.
+			See also Documentation/sysctl/vm.txt
+
 	reserve=	[KNL,BUGS] Force the kernel to ignore some iomem area
 
 	reservetop=	[X86-32]
Index: linux-2.6.21-rc7-mm2/Documentation/sysctl/vm.txt
===================================================================
--- linux-2.6.21-rc7-mm2.orig/Documentation/sysctl/vm.txt
+++ linux-2.6.21-rc7-mm2/Documentation/sysctl/vm.txt
@@ -34,6 +34,7 @@ Currently, these files are in /proc/sys/
 - swap_prefetch
 - readahead_ratio
 - readahead_hit_rate
+- numa_zonelist_order
 
 ==============================================================
 
@@ -275,3 +276,34 @@ Possible values can be:
 The larger value, the more capabilities, with more possible overheads.
 
 The default value is 1.
+
+=============================================================
+
+numa_zonelist_order
+
+This sysctl is only for NUMA.
+
+numa_zonelist_order selects the order of the memory allocation zonelists.
+The default order [a.k.a. "node order"] orders the zonelists by node, the
+by zone within each node. The default is automatic configuration.
+Specify "[Dd]fault" or "0" to request automatic configuration.
+
+ For example, assume 2 Node NUMA.  The "Node order" kernel memory allocation
+order on Node(0) will be:
+
+	Node(0)NORMAL -> Node(0)DMA -> Node(1)NORMAL -> Node(1)DMA(if any)
+
+Thus, allocations that request Node(0) NORMAL may overflow onto Node(0)DMA
+first.  This provides maximum locality, but risks exhausting all of DMA
+memory while NORMAL memory exists elsewhere on the system.  This can result
+in OOM-KILL in ZONE_DMA.  Secify "[Zz]one" or "1" to request zone order.
+
+If numa_zonelist_order is set to "node" order, the kernel memory allocation
+order on Node(0) becomes:
+
+	Node(0)NORMAL -> Node(1)NORMAL -> Node(0)DMA -> Node(1)DMA(if any)
+
+In this mode, DMA memory will be used in place of NORMAL memory, only when
+all NORMAL zones are exhausted.  Specify "[Nn]ode" or "2" for node order.
+
+The default value is 0.

-
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