[PATCH] change global zonelist order on NUMA v2

KAMEZAWA Hiroyuki
2007-04-26T09:34:48Z

Changelog from V1 -> V2
- sysctl name is changed to be relaxed_zone_order
- NORMAL->NORMAL->....->DMA->DMA->DMA order (new ordering) is now default.
NORMAL->DMA->NORMAL->DMA order (old ordering) is optional.
- addes boot opttion to set relaxed_zone_order. ia64 is supported now.
- Added documentation

patch is against 2.6.21-rc7-mm2. tested on ia64 NUMA box. works well.

-Kame
> from hrere

Make zonelist creation policy selectable from sysctl v2.

[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 1 > /proc/sys/vm/relaxed_zone_order

Will rebuild zonelist in following order(old style).

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

And you can specify "relaxed_zone_order" boot option if supported by arch.
But this style zonelist can easily cause OOM-Kill because of ZONE_DMA
exhaition. be careful.

command:
echo 0 > /proc/sys/vm/relaxed_zone_order
will rebuild zonelist as
Node(0)'s NORMAL -> Node(1)'s NORMAL -> Node(0)'s DMA.

Added ia64 support and tested on ia64 2-Node NUMA. works well.

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

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
@@ -80,6 +80,7 @@ extern int sysctl_drop_caches;
extern int percpu_pagelist_fraction;
extern int compat_log;
extern int maps_protect;
+extern int sysctl_relaxed_zone_order;

#if defined(CONFIG_ADAPTIVE_READAHEAD)
extern int readahead_ratio;
@@ -893,6 +894,15 @@ static ctl_table vm_table[] = {
.extra1 = &zero,
.extra2 = &one_hundred,
},
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "relaxed_zone_order",
+ .data = &sysctl_relaxed_zone_order,
+ .maxlen = sizeof(sysctl_relaxed_zone_order),
+ .mode = 0644,
+ .proc_handler = &sysctl_relaxed_zone_order_handler,
+ .strategy = &sysctl_intvec,
+ },
#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
@@ -2045,7 +2045,7 @@ 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 +2060,7 @@ 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;
@@ -2106,7 +2106,10 @@ static int __meminit find_next_best_node
return best_node;
}

-static void __meminit build_zonelists(pg_data_t *pgdat)
+/*
+ * Build zonelists based on node locality.
+ */
+static void build_zonelists_locality_aware(pg_data_t *pgdat)
{
int j, node, local_node;
enum zone_type i;
@@ -2155,6 +2158,81 @@ static void __meminit build_zonelists(pg
}
}

+/*
+ * Build zonelist based on zone priority.
+ */
+static int node_order[MAX_NUMNODES];
+static void build_zonelists_zone_aware(pg_data_t *pgdat)
+{
+ int i, j, pos, zone_type, node, load;
+ nodemask_t used_mask;
+ int local_node, prev_node;
+ struct zone *z;
+ struct zonelist *zonelist;
+
+ for (i = 0; i < MAX_NR_ZONES; i++) {
+ zonelist = pgdat->node_zonelists + i;
+ zonelist->zones[0] = NULL;
+ }
+ memset(node_order, 0, sizeof(node_order));
+ local_node = pgdat->node_id;
+ load = num_online_nodes();
+ prev_node = local_node;
+ nodes_clear(used_mask);
+ j = 0;
+ while ((node = find_next_best_node(local_node, &used_mask)) >= 0) {
+ int distance = node_distance(local_node, node);
+ if (distance > RECLAIM_DISTANCE)
+ zone_reclaim_mode = 1;
+ if (distance != node_distance(local_node, prev_node))
+ node_load[node] = load;
+ node_order[j++] = node;
+ prev_node = node;
+ load--;
+ }
+ /* calculate node order */
+ 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 < num_online_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;
+ }
+}
+
+int sysctl_relaxed_zone_order = 0;
+
+static void build_zonelists(pg_data_t *pgdat)
+{
+ if (sysctl_relaxed_zone_order)
+ build_zonelists_locality_aware(pgdat);
+ else
+ build_zonelists_zone_aware(pgdat);
+}
+
+int sysctl_relaxed_zone_order_handler(ctl_table *table, int write,
+ struct file *file, void __user *buffer, size_t *length,
+ loff_t *ppos)
+{
+ int oldval = sysctl_relaxed_zone_order;
+ proc_dointvec_minmax(table, write, file, buffer, length, ppos);
+ if (write && (oldval != sysctl_relaxed_zone_order))
+ build_all_zonelists();
+ return 0;
+}
+
+int __init cmdline_parse_relaxed_zone_order(char *p)
+{
+ sysctl_relaxed_zone_order = 1;
+ return 0;
+}
+
/* Construct the zonelist performance cache - see further mmzone.h */
static void __meminit build_zonelist_cache(pg_data_t *pgdat)
{
@@ -2222,7 +2300,7 @@ 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 +2311,13 @@ 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 sysctl_relaxed_zone_order_handler(struct ctl_table *, int,
+ struct file *, void __user *, size_t *, loff_t *);
+
+extern int cmdline_parse_relaxed_zone_order(char *p);
+
#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 +1500,10 @@ and is between 256 and 4096 characters.
Format: <reboot_mode>[,<reboot_mode2>[,...]]
See arch/*/kernel/reboot.c or arch/*/kernel/process.c

+ relaxed_zone_order [KNL,BOOT]
+ give memory allocation priority to locality rather
+ than zone class. See 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
+- relaxed_zone_order

==============================================================

@@ -275,3 +276,24 @@ Possible values can be:
The larger value, the more capabilities, with more possible overheads.

The default value is 1.
+
+=============================================================
+
+relaxed_zone_order
+
+This sysctl is only for NUMA.
+This allows you to allocate local memory more aggresively.
+Assume 2 Node NUMA.The kernel memory allocateion order on Node(0)
+is following. relaxed_zone_order=0 in this case.(default)
+==
+Node(0)NORMAL -> Node(1)NORMAL -> Node(0)DMA -> Node(1)DMA(if any)
+==
+If set to relaxed_zone_order=1, This option changes this order to be
+==
+Node(0)NORMAL -> Node(0)DMA -> Node(1)NORMA -> Node(1)DMA
+==
+Then you can use more local memory. But, in this case, ZONE_DMA can be
+used more eagerly than default. Then, OOM-KILL in ZONE_DMA can happen easier.
+
+The default value is 0.
+
Index: linux-2.6.21-rc7-mm2/arch/ia64/mm/discontig.c
===================================================================
--- linux-2.6.21-rc7-mm2.orig/arch/ia64/mm/discontig.c
+++ linux-2.6.21-rc7-mm2/arch/ia64/mm/discontig.c
@@ -27,6 +27,8 @@
#include <asm/numa.h>
#include <asm/sections.h>

+
+early_param("relaxed_zone_order", cmdline_parse_relaxed_zone_order);
/*
* Track per-node information needed to setup the boot memory allocator, the
* per-node areas, and the real VM.