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Date: Thu, 19 Mar 2009 16:43:55 -0400 (EDT)
From: Christoph Lameter <cl@...ux-foundation.org>
To: Mel Gorman <mel@....ul.ie>
cc: Linux Memory Management List <linux-mm@...ck.org>,
Pekka Enberg <penberg@...helsinki.fi>,
Rik van Riel <riel@...hat.com>,
KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
Johannes Weiner <hannes@...xchg.org>,
Nick Piggin <npiggin@...e.de>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Lin Ming <ming.m.lin@...el.com>,
Zhang Yanmin <yanmin_zhang@...ux.intel.com>,
Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH 20/35] Use a pre-calculated value for
num_online_nodes()
Trying to the same in the style of nr_node_ids etc.
Subject: Provide nr_online_nodes and nr_possible_nodes
It seems that its beneficial to have a less expensive way to check for the
number of currently active and possible nodes in a NUMA system. This will
simplify further kernel optimizations for the cases in which only a single
node is online or possible.
Signed-off-by: Christoph Lameter <cl@...ux-foundation.org>
Index: linux-2.6/include/linux/nodemask.h
===================================================================
--- linux-2.6.orig/include/linux/nodemask.h 2009-03-19 15:04:28.000000000 -0500
+++ linux-2.6/include/linux/nodemask.h 2009-03-19 15:33:18.000000000 -0500
@@ -408,6 +408,20 @@
#define next_online_node(nid) next_node((nid), node_states[N_ONLINE])
extern int nr_node_ids;
+extern int nr_online_nodes;
+extern int nr_possible_nodes;
+
+static inline void node_set_online(int nid)
+{
+ node_set_state(nid, N_ONLINE);
+ nr_online_nodes = num_node_state(N_ONLINE);
+}
+
+static inline void node_set_offline(int nid)
+{
+ node_clear_state(nid, N_ONLINE);
+ nr_online_nodes = num_node_state(N_ONLINE);
+}
#else
static inline int node_state(int node, enum node_states state)
@@ -434,7 +448,8 @@
#define first_online_node 0
#define next_online_node(nid) (MAX_NUMNODES)
#define nr_node_ids 1
-
+#define nr_online_nodes 1
+#define nr_possible_nodes 1
#endif
#define node_online_map node_states[N_ONLINE]
@@ -454,8 +469,7 @@
#define node_online(node) node_state((node), N_ONLINE)
#define node_possible(node) node_state((node), N_POSSIBLE)
-#define node_set_online(node) node_set_state((node), N_ONLINE)
-#define node_set_offline(node) node_clear_state((node), N_ONLINE)
+
#define for_each_node(node) for_each_node_state(node, N_POSSIBLE)
#define for_each_online_node(node) for_each_node_state(node, N_ONLINE)
Index: linux-2.6/mm/hugetlb.c
===================================================================
--- linux-2.6.orig/mm/hugetlb.c 2009-03-19 15:11:49.000000000 -0500
+++ linux-2.6/mm/hugetlb.c 2009-03-19 15:12:13.000000000 -0500
@@ -875,7 +875,7 @@
* can no longer free unreserved surplus pages. This occurs when
* the nodes with surplus pages have no free pages.
*/
- unsigned long remaining_iterations = num_online_nodes();
+ unsigned long remaining_iterations = nr_online_nodes;
/* Uncommit the reservation */
h->resv_huge_pages -= unused_resv_pages;
@@ -904,7 +904,7 @@
h->surplus_huge_pages--;
h->surplus_huge_pages_node[nid]--;
nr_pages--;
- remaining_iterations = num_online_nodes();
+ remaining_iterations = nr_online_nodes;
}
}
}
Index: linux-2.6/mm/page_alloc.c
===================================================================
--- linux-2.6.orig/mm/page_alloc.c 2009-03-19 15:12:19.000000000 -0500
+++ linux-2.6/mm/page_alloc.c 2009-03-19 15:30:21.000000000 -0500
@@ -168,6 +168,10 @@
#if MAX_NUMNODES > 1
int nr_node_ids __read_mostly = MAX_NUMNODES;
EXPORT_SYMBOL(nr_node_ids);
+int nr_online_nodes __read_mostly = 1;
+EXPORT_SYMBOL(nr_online_nodes);
+int nr_possible_nodes __read_mostly = MAX_NUMNODES;
+EXPORT_SYMBOL(nr_possible_nodes);
#endif
int page_group_by_mobility_disabled __read_mostly;
@@ -2115,7 +2119,7 @@
}
-#define MAX_NODE_LOAD (num_online_nodes())
+#define MAX_NODE_LOAD nr_online_nodes
static int node_load[MAX_NUMNODES];
/**
Index: linux-2.6/mm/slab.c
===================================================================
--- linux-2.6.orig/mm/slab.c 2009-03-19 15:13:45.000000000 -0500
+++ linux-2.6/mm/slab.c 2009-03-19 15:15:28.000000000 -0500
@@ -881,7 +881,6 @@
*/
static int use_alien_caches __read_mostly = 1;
-static int numa_platform __read_mostly = 1;
static int __init noaliencache_setup(char *s)
{
use_alien_caches = 0;
@@ -1434,9 +1433,8 @@
int order;
int node;
- if (num_possible_nodes() == 1) {
+ if (nr_possible_nodes == 1) {
use_alien_caches = 0;
- numa_platform = 0;
}
for (i = 0; i < NUM_INIT_LISTS; i++) {
@@ -3526,7 +3524,7 @@
* variable to skip the call, which is mostly likely to be present in
* the cache.
*/
- if (numa_platform && cache_free_alien(cachep, objp))
+ if (nr_possible_nodes > 1 && cache_free_alien(cachep, objp))
return;
if (likely(ac->avail < ac->limit)) {
Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c 2009-03-19 15:13:15.000000000 -0500
+++ linux-2.6/mm/slub.c 2009-03-19 15:13:38.000000000 -0500
@@ -3648,7 +3648,7 @@
to_cpumask(l->cpus));
}
- if (num_online_nodes() > 1 && !nodes_empty(l->nodes) &&
+ if (nr_online_nodes > 1 && !nodes_empty(l->nodes) &&
len < PAGE_SIZE - 60) {
len += sprintf(buf + len, " nodes=");
len += nodelist_scnprintf(buf + len, PAGE_SIZE - len - 50,
Index: linux-2.6/net/sunrpc/svc.c
===================================================================
--- linux-2.6.orig/net/sunrpc/svc.c 2009-03-19 15:16:21.000000000 -0500
+++ linux-2.6/net/sunrpc/svc.c 2009-03-19 15:16:51.000000000 -0500
@@ -124,7 +124,7 @@
{
unsigned int node;
- if (num_online_nodes() > 1) {
+ if (nr_online_nodes > 1) {
/*
* Actually have multiple NUMA nodes,
* so split pools on NUMA node boundaries
--
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