In my last posintg, mempolicy-fix-for-memory-less-node patch, there was a
discussion 'what do you consider definition of "node" as...?
I found there is no consensus. But I want to go ahead.
Before posing patch again, I'd like to discuss more.
-Kame
In my understanding, a "node" is a block of cpu, memory, devices.
and there could be cpu-only-node, memory-only-node, device-only-node...
There will be discussion. IMHO, to represent hardware configuration
as it is, this definition is very natural and flexible.
(And because my work is memory-hotplug, this definition fits me.)
"Don't support such crazy configuraton" is one of opinions.
I hear x86_64 doesn't support it and defines node as a block of memory,
It remaps cpus on memory-less-nodes to other nodes.
I know ia64 allows memory-less-node. (I don't know about ppc.)
It works well on my box (and HP's box).
If there is memory-less-node, codes which checks all nodes which have memory
should check NODE_DATA(nid)->present_pages.
But following is a bit heavy operation.
xxxxx
for_each_online_node(nid)
if (!node_present_pages(nid))
continue;
xxxxx
This patch adds a new node mask "node_memory_online_map" for nodes
which have memory.
for_each_node_mask(nid, node_memory_online_map) walks all memory-ready-nodes.
This mask is updated at node-hotplug ops.
Signed-Off-By: KAMEZAWA Hiroyuki <[EMAIL PROTECTED]>
Index: linux-2.6.20/include/linux/nodemask.h
===================================================================
--- linux-2.6.20.orig/include/linux/nodemask.h 2007-02-07 17:25:54.000000000
+0900
+++ linux-2.6.20/include/linux/nodemask.h 2007-02-13 15:31:33.000000000
+0900
@@ -344,6 +344,8 @@
extern nodemask_t node_online_map;
extern nodemask_t node_possible_map;
+/* online nodes which have memory */
+extern nodemask_t node_memory_online_map;
#if MAX_NUMNODES > 1
#define num_online_nodes() nodes_weight(node_online_map)
Index: linux-2.6.20/mm/page_alloc.c
===================================================================
--- linux-2.6.20.orig/mm/page_alloc.c 2007-02-07 17:25:54.000000000 +0900
+++ linux-2.6.20/mm/page_alloc.c 2007-02-13 15:54:04.000000000 +0900
@@ -54,6 +54,9 @@
EXPORT_SYMBOL(node_online_map);
nodemask_t node_possible_map __read_mostly = NODE_MASK_ALL;
EXPORT_SYMBOL(node_possible_map);
+nodemask_t node_memory_online_map __read_mostly = { { [0] = 1UL } };
+EXPORT_SYMBOL(node_memory_online_map);
+
unsigned long totalram_pages __read_mostly;
unsigned long totalreserve_pages __read_mostly;
long nr_swap_pages;
@@ -1805,6 +1808,16 @@
}
}
+static void __meminit fixup_memory_online_nodes(void)
+{
+ int nid;
+ nodes_clear(node_memory_online_map);
+ for_each_online_node(nid) {
+ if (node_present_pages(nid))
+ node_set(nid, node_memory_online_map);
+ }
+}
+
#else /* CONFIG_NUMA */
static void __meminit build_zonelists(pg_data_t *pgdat)
@@ -1851,6 +1864,10 @@
pgdat->node_zonelists[i].zlcache_ptr = NULL;
}
+static void fixup_memory_online_nodes(void)
+{
+ return;
+}
#endif /* CONFIG_NUMA */
/* return values int ....just for stop_machine_run() */
@@ -1862,6 +1879,7 @@
build_zonelists(NODE_DATA(nid));
build_zonelist_cache(NODE_DATA(nid));
}
+ fixup_memory_online_nodes();
return 0;
}
-
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