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

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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