change zonelist order: zonelist order selection logic
Make zonelist creation policy selectable from sysctl/boot option v6.
This patch makes NUMA's zonelist (of pgdat) order selectable.
Available order are Default(automatic)/ Node-based / Zone-based.
[Default Order]
The kernel selects Node-based or Zone-based order automatically.
[Node-based Order]
This policy treats the locality of memory as the most important parameter.
Zonelist order is created by each zone's locality. This means lower zones
(ex. ZONE_DMA) can be used before higher zone (ex. ZONE_NORMAL) exhausion.
IOW. ZONE_DMA will be in the middle of zonelist.
current 2.6.21 kernel uses this.
Pros.
* A user can expect local memory as much as possible.
Cons.
* lower zone will be exhansted before higher zone. This may cause OOM_KILL.
Maybe suitable if ZONE_DMA is relatively big and you never see OOM_KILL
because of ZONE_DMA exhaution and you need the best locality.
(example)
assume 2 node NUMA. node(0) has ZONE_DMA/ZONE_NORMAL, node(1) has ZONE_NORMAL.
*node(0)'s memory allocation order:
node(0)'s NORMAL -> node(0)'s DMA -> node(1)'s NORMAL.
*node(1)'s memory allocation order:
node(1)'s NORMAL -> node(0)'s NORMAL -> node(0)'s DMA.
[Zone-based order]
This policy treats the zone type as the most important parameter.
Zonelist order is created by zone-type order. This means lower zone
never be used bofere higher zone exhaustion.
IOW. ZONE_DMA will be always at the tail of zonelist.
Pros.
* OOM_KILL(bacause of lower zone) occurs only if the whole zones are exhausted.
Cons.
* memory locality may not be best.
(example)
assume 2 node NUMA. node(0) has ZONE_DMA/ZONE_NORMAL, node(1) has ZONE_NORMAL.
*node(0)'s memory allocation order:
node(0)'s NORMAL -> node(1)'s NORMAL -> node(0)'s DMA.
*node(1)'s memory allocation order:
node(1)'s NORMAL -> node(0)'s NORMAL -> node(0)'s DMA.
bootoption "numa_zonelist_order=" and proc/sysctl is supporetd.
command:
%echo N > /proc/sys/vm/numa_zonelist_order
Will rebuild zonelist in Node-based order.
command:
%echo Z > /proc/sys/vm/numa_zonelist_order
Will rebuild zonelist in Zone-based order.
Thanks to Lee Schermerhorn, he gives me much help and codes.
[Lee.Schermerhorn@hp.com: add check_highest_zone to build_zonelists_in_zone_order]
[akpm@linux-foundation.org: build fix]
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Andi Kleen <ak@suse.de>
Cc: "jesse.barnes@intel.com" <jesse.barnes@intel.com>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 62aab58..4344f69 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1196,6 +1196,11 @@
nowb [ARM]
+ numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
+ one of ['zone', 'node', 'default'] can be specified
+ This can be set from sysctl after boot.
+ See Documentation/sysctl/vm.txt for details.
+
nr_uarts= [SERIAL] maximum number of UARTs to be registered.
opl3= [HW,OSS]
diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index 8cfca17..df3ff20 100644
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -32,6 +32,7 @@
- min_slab_ratio
- panic_on_oom
- mmap_min_address
+- numa_zonelist_order
==============================================================
@@ -231,3 +232,47 @@
vast majority of applications to work correctly and provide defense in depth
against future potential kernel bugs.
+==============================================================
+
+numa_zonelist_order
+
+This sysctl is only for NUMA.
+'where the memory is allocated from' is controlled by zonelists.
+(This documentation ignores ZONE_HIGHMEM/ZONE_DMA32 for simple explanation.
+ you may be able to read ZONE_DMA as ZONE_DMA32...)
+
+In non-NUMA case, a zonelist for GFP_KERNEL is ordered as following.
+ZONE_NORMAL -> ZONE_DMA
+This means that a memory allocation request for GFP_KERNEL will
+get memory from ZONE_DMA only when ZONE_NORMAL is not available.
+
+In NUMA case, you can think of following 2 types of order.
+Assume 2 node NUMA and below is zonelist of Node(0)'s GFP_KERNEL
+
+(A) Node(0) ZONE_NORMAL -> Node(0) ZONE_DMA -> Node(1) ZONE_NORMAL
+(B) Node(0) ZONE_NORMAL -> Node(1) ZONE_NORMAL -> Node(0) ZONE_DMA.
+
+Type(A) offers the best locality for processes on Node(0), but ZONE_DMA
+will be used before ZONE_NORMAL exhaustion. This increases possibility of
+out-of-memory(OOM) of ZONE_DMA because ZONE_DMA is tend to be small.
+
+Type(B) cannot offer the best locality but is more robust against OOM of
+the DMA zone.
+
+Type(A) is called as "Node" order. Type (B) is "Zone" order.
+
+"Node order" orders the zonelists by node, then by zone within each node.
+Specify "[Nn]ode" for zone order
+
+"Zone Order" orders the zonelists by zone type, then by node within each
+zone. Specify "[Zz]one"for zode order.
+
+Specify "[Dd]efault" to request automatic configuration. Autoconfiguration
+will select "node" order in following case.
+(1) if the DMA zone does not exist or
+(2) if the DMA zone comprises greater than 50% of the available memory or
+(3) if any node's DMA zone comprises greater than 60% of its local memory and
+ the amount of local memory is big enough.
+
+Otherwise, "zone" order will be selected. Default order is recommended unless
+this is causing problems for your system/application.
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index d09b134..04b1636 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -566,6 +566,11 @@
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
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index d93e13d..ccaebbb 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -958,6 +958,17 @@
.mode = 0644,
.proc_handler = &proc_doulongvec_minmax,
},
+#ifdef CONFIG_NUMA
+ {
+ .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
#endif
#if defined(CONFIG_X86_32) || \
(defined(CONFIG_SUPERH) && defined(CONFIG_VSYSCALL))
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 05ace44..092b2d8 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1621,8 +1621,8 @@
*
* 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)
+static int build_zonelists_node(pg_data_t *pgdat, struct zonelist *zonelist,
+ int nr_zones, enum zone_type zone_type)
{
struct zone *zone;
@@ -1641,9 +1641,102 @@
return nr_zones;
}
+
+/*
+ * zonelist_order:
+ * 0 = automatic detection of better ordering.
+ * 1 = order by ([node] distance, -zonetype)
+ * 2 = order by (-zonetype, [node] distance)
+ *
+ * If not NUMA, ZONELIST_ORDER_ZONE and ZONELIST_ORDER_NODE will create
+ * the same zonelist. So only NUMA can configure this param.
+ */
+#define ZONELIST_ORDER_DEFAULT 0
+#define ZONELIST_ORDER_NODE 1
+#define ZONELIST_ORDER_ZONE 2
+
+/* zonelist order in the kernel.
+ * set_zonelist_order() will set this to NODE or ZONE.
+ */
+static int current_zonelist_order = ZONELIST_ORDER_DEFAULT;
+static char zonelist_order_name[3][8] = {"Default", "Node", "Zone"};
+
+
#ifdef CONFIG_NUMA
+/* The value user specified ....changed by config */
+static int user_zonelist_order = ZONELIST_ORDER_DEFAULT;
+/* string for sysctl */
+#define NUMA_ZONELIST_ORDER_LEN 16
+char numa_zonelist_order[16] = "default";
+
+/*
+ * interface for configure zonelist ordering.
+ * command line option "numa_zonelist_order"
+ * = "[dD]efault - default, automatic configuration.
+ * = "[nN]ode - order by node locality, then by zone within node
+ * = "[zZ]one - order by zone, then by locality within zone
+ */
+
+static int __parse_numa_zonelist_order(char *s)
+{
+ if (*s == 'd' || *s == 'D') {
+ user_zonelist_order = ZONELIST_ORDER_DEFAULT;
+ } else if (*s == 'n' || *s == 'N') {
+ user_zonelist_order = ZONELIST_ORDER_NODE;
+ } else if (*s == 'z' || *s == 'Z') {
+ user_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);
+
+/*
+ * 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 = user_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);
+ user_zonelist_order = oldval;
+ } else if (oldval != user_zonelist_order)
+ build_all_zonelists();
+ }
+ return 0;
+}
+
+
#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
@@ -1658,7 +1751,7 @@
* 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;
@@ -1704,13 +1797,129 @@
return best_node;
}
-static void __meminit build_zonelists(pg_data_t *pgdat)
+
+/*
+ * 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;
+ check_highest_zone(zone_type);
+ }
+ }
+ }
+ zonelist->zones[pos] = NULL;
+ }
+}
+
+static int default_zonelist_order(void)
+{
+ int nid, zone_type;
+ unsigned long low_kmem_size,total_size;
+ struct zone *z;
+ int average_size;
+ /*
+ * ZONE_DMA and ZONE_DMA32 can be very small area in the sytem.
+ * If they are really small and used heavily, the system can fall
+ * into OOM very easily.
+ * This function detect ZONE_DMA/DMA32 size and confgigures zone order.
+ */
+ /* Is there ZONE_NORMAL ? (ex. ppc has only DMA zone..) */
+ low_kmem_size = 0;
+ total_size = 0;
+ for_each_online_node(nid) {
+ for (zone_type = 0; zone_type < MAX_NR_ZONES; zone_type++) {
+ z = &NODE_DATA(nid)->node_zones[zone_type];
+ if (populated_zone(z)) {
+ if (zone_type < ZONE_NORMAL)
+ low_kmem_size += z->present_pages;
+ total_size += z->present_pages;
+ }
+ }
+ }
+ if (!low_kmem_size || /* there are no DMA area. */
+ low_kmem_size > total_size/2) /* DMA/DMA32 is big. */
+ return ZONELIST_ORDER_NODE;
+ /*
+ * look into each node's config.
+ * If there is a node whose DMA/DMA32 memory is very big area on
+ * local memory, NODE_ORDER may be suitable.
+ */
+ average_size = total_size / (num_online_nodes() + 1);
+ for_each_online_node(nid) {
+ low_kmem_size = 0;
+ total_size = 0;
+ for (zone_type = 0; zone_type < MAX_NR_ZONES; zone_type++) {
+ z = &NODE_DATA(nid)->node_zones[zone_type];
+ if (populated_zone(z)) {
+ if (zone_type < ZONE_NORMAL)
+ low_kmem_size += z->present_pages;
+ total_size += z->present_pages;
+ }
+ }
+ if (low_kmem_size &&
+ total_size > average_size && /* ignore small node */
+ low_kmem_size > total_size * 70/100)
+ return ZONELIST_ORDER_NODE;
+ }
+ return ZONELIST_ORDER_ZONE;
+}
+
+static void set_zonelist_order(void)
+{
+ if (user_zonelist_order == ZONELIST_ORDER_DEFAULT)
+ current_zonelist_order = default_zonelist_order();
+ else
+ current_zonelist_order = user_zonelist_order;
+}
+
+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 order = current_zonelist_order;
/* initialize zonelists */
for (i = 0; i < MAX_NR_ZONES; i++) {
@@ -1723,6 +1932,11 @@
load = num_online_nodes();
prev_node = local_node;
nodes_clear(used_mask);
+
+ memset(node_load, 0, sizeof(node_load));
+ 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);
@@ -1738,23 +1952,25 @@
* 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 (order == ZONELIST_ORDER_NODE)
+ 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 (order == ZONELIST_ORDER_ZONE) {
+ /* calculate node order -- i.e., DMA last! */
+ build_zonelists_in_zone_order(pgdat, j);
}
}
/* Construct the zonelist performance cache - see further mmzone.h */
-static void __meminit build_zonelist_cache(pg_data_t *pgdat)
+static void build_zonelist_cache(pg_data_t *pgdat)
{
int i;
@@ -1771,9 +1987,15 @@
}
}
+
#else /* CONFIG_NUMA */
-static void __meminit build_zonelists(pg_data_t *pgdat)
+static void set_zonelist_order(void)
+{
+ current_zonelist_order = ZONELIST_ORDER_ZONE;
+}
+
+static void build_zonelists(pg_data_t *pgdat)
{
int node, local_node;
enum zone_type i,j;
@@ -1809,7 +2031,7 @@
}
/* non-NUMA variant of zonelist performance cache - just NULL zlcache_ptr */
-static void __meminit build_zonelist_cache(pg_data_t *pgdat)
+static void build_zonelist_cache(pg_data_t *pgdat)
{
int i;
@@ -1820,7 +2042,7 @@
#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;
@@ -1831,8 +2053,10 @@
return 0;
}
-void __meminit build_all_zonelists(void)
+void build_all_zonelists(void)
{
+ set_zonelist_order();
+
if (system_state == SYSTEM_BOOTING) {
__build_all_zonelists(NULL);
cpuset_init_current_mems_allowed();
@@ -1843,8 +2067,13 @@
/* cpuset refresh routine should be here */
}
vm_total_pages = nr_free_pagecache_pages();
- printk("Built %i zonelists. Total pages: %ld\n",
- num_online_nodes(), vm_total_pages);
+ printk("Built %i zonelists in %s order. Total pages: %ld\n",
+ num_online_nodes(),
+ zonelist_order_name[current_zonelist_order],
+ vm_total_pages);
+#ifdef CONFIG_NUMA
+ printk("Policy zone: %s\n", zone_names[policy_zone]);
+#endif
}
/*