Memoryless nodes: Generic management of nodemasks for various purposes
Why do we need to support memoryless nodes?
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> For fujitsu, problem is called "empty" node.
>
> When ACPI's SRAT table includes "possible nodes", ia64 bootstrap(acpi_numa_init)
> creates nodes, which includes no memory, no cpu.
>
> I tried to remove empty-node in past, but that was denied.
> It was because we can hot-add cpu to the empty node.
> (node-hotplug triggered by cpu is not implemented now. and it will be ugly.)
>
>
> For HP, (Lee can comment on this later), they have memory-less-node.
> As far as I hear, HP's machine can have following configration.
>
> (example)
> Node0: CPU0 memory AAA MB
> Node1: CPU1 memory AAA MB
> Node2: CPU2 memory AAA MB
> Node3: CPU3 memory AAA MB
> Node4: Memory XXX GB
>
> AAA is very small value (below 16MB) and will be omitted by ia64 bootstrap.
> After boot, only Node 4 has valid memory (but have no cpu.)
>
> Maybe this is memory-interleave by firmware config.
Christoph Lameter <clameter@sgi.com> wrote:
> Future SGI platforms (actually also current one can have but nothing like
> that is deployed to my knowledge) have nodes with only cpus. Current SGI
> platforms have nodes with just I/O that we so far cannot manage in the
> core. So the arch code maps them to the nearest memory node.
Lee Schermerhorn <Lee.Schermerhorn@hp.com> wrote:
> For the HP platforms, we can configure each cell with from 0% to 100%
> "cell local memory". When we configure with <100% CLM, the "missing
> percentages" are interleaved by hardware on a cache-line granularity to
> improve bandwidth at the expense of latency for numa-challenged
> applications [and OSes, but not our problem ;-)]. When we boot Linux on
> such a config, all of the real nodes have no memory--it all resides in a
> single interleaved pseudo-node.
>
> When we boot Linux on a 100% CLM configuration [== NUMA], we still have
> the interleaved pseudo-node. It contains a few hundred MB stolen from
> the real nodes to contain the DMA zone. [Interleaved memory resides at
> phys addr 0]. The memoryless-nodes patches, along with the zoneorder
> patches, support this config as well.
>
> Also, when we boot a NUMA config with the "mem=" command line,
> specifying less memory than actually exists, Linux takes the excluded
> memory "off the top" rather than distributing it across the nodes. This
> can result in memoryless nodes, as well.
>
This patch:
Preparation for memoryless node patches.
Provide a generic way to keep nodemasks describing various characteristics of
NUMA nodes.
Remove the node_online_map and the node_possible map and realize the same
functionality using two nodes stats: N_POSSIBLE and N_ONLINE.
[Lee.Schermerhorn@hp.com: Initialize N_*_MEMORY and N_CPU masks for non-NUMA config]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Tested-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Acked-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Acked-by: Bob Picco <bob.picco@hp.com>
Cc: Nishanth Aravamudan <nacc@us.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@skynet.ie>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/nodemask.h b/include/linux/nodemask.h
index 52c54a5..583e6b8 100644
--- a/include/linux/nodemask.h
+++ b/include/linux/nodemask.h
@@ -338,31 +338,81 @@
#endif /* MAX_NUMNODES */
/*
+ * Bitmasks that are kept for all the nodes.
+ */
+enum node_states {
+ N_POSSIBLE, /* The node could become online at some point */
+ N_ONLINE, /* The node is online */
+ NR_NODE_STATES
+};
+
+/*
* The following particular system nodemasks and operations
* on them manage all possible and online nodes.
*/
-extern nodemask_t node_online_map;
-extern nodemask_t node_possible_map;
+extern nodemask_t node_states[NR_NODE_STATES];
#if MAX_NUMNODES > 1
-#define num_online_nodes() nodes_weight(node_online_map)
-#define num_possible_nodes() nodes_weight(node_possible_map)
-#define node_online(node) node_isset((node), node_online_map)
-#define node_possible(node) node_isset((node), node_possible_map)
-#define first_online_node first_node(node_online_map)
-#define next_online_node(nid) next_node((nid), node_online_map)
+static inline int node_state(int node, enum node_states state)
+{
+ return node_isset(node, node_states[state]);
+}
+
+static inline void node_set_state(int node, enum node_states state)
+{
+ __node_set(node, &node_states[state]);
+}
+
+static inline void node_clear_state(int node, enum node_states state)
+{
+ __node_clear(node, &node_states[state]);
+}
+
+static inline int num_node_state(enum node_states state)
+{
+ return nodes_weight(node_states[state]);
+}
+
+#define for_each_node_state(__node, __state) \
+ for_each_node_mask((__node), node_states[__state])
+
+#define first_online_node first_node(node_states[N_ONLINE])
+#define next_online_node(nid) next_node((nid), node_states[N_ONLINE])
+
extern int nr_node_ids;
#else
-#define num_online_nodes() 1
-#define num_possible_nodes() 1
-#define node_online(node) ((node) == 0)
-#define node_possible(node) ((node) == 0)
+
+static inline int node_state(int node, enum node_states state)
+{
+ return node == 0;
+}
+
+static inline void node_set_state(int node, enum node_states state)
+{
+}
+
+static inline void node_clear_state(int node, enum node_states state)
+{
+}
+
+static inline int num_node_state(enum node_states state)
+{
+ return 1;
+}
+
+#define for_each_node_state(node, __state) \
+ for ( (node) = 0; (node) == 0; (node) = 1)
+
#define first_online_node 0
#define next_online_node(nid) (MAX_NUMNODES)
#define nr_node_ids 1
+
#endif
+#define node_online_map node_states[N_ONLINE]
+#define node_possible_map node_states[N_POSSIBLE]
+
#define any_online_node(mask) \
({ \
int node; \
@@ -372,10 +422,15 @@
node; \
})
-#define node_set_online(node) set_bit((node), node_online_map.bits)
-#define node_set_offline(node) clear_bit((node), node_online_map.bits)
+#define num_online_nodes() num_node_state(N_ONLINE)
+#define num_possible_nodes() num_node_state(N_POSSIBLE)
+#define node_online(node) node_state((node), N_ONLINE)
+#define node_possible(node) node_state((node), N_POSSIBLE)
-#define for_each_node(node) for_each_node_mask((node), node_possible_map)
-#define for_each_online_node(node) for_each_node_mask((node), node_online_map)
+#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)
#endif /* __LINUX_NODEMASK_H */
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 71013e6..0cc5b3e 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -47,13 +47,21 @@
#include "internal.h"
/*
- * MCD - HACK: Find somewhere to initialize this EARLY, or make this
- * initializer cleaner
+ * Array of node states.
*/
-nodemask_t node_online_map __read_mostly = { { [0] = 1UL } };
-EXPORT_SYMBOL(node_online_map);
-nodemask_t node_possible_map __read_mostly = NODE_MASK_ALL;
-EXPORT_SYMBOL(node_possible_map);
+nodemask_t node_states[NR_NODE_STATES] __read_mostly = {
+ [N_POSSIBLE] = NODE_MASK_ALL,
+ [N_ONLINE] = { { [0] = 1UL } },
+#ifndef CONFIG_NUMA
+ [N_NORMAL_MEMORY] = { { [0] = 1UL } },
+#ifdef CONFIG_HIGHMEM
+ [N_HIGH_MEMORY] = { { [0] = 1UL } },
+#endif
+ [N_CPU] = { { [0] = 1UL } },
+#endif /* NUMA */
+};
+EXPORT_SYMBOL(node_states);
+
unsigned long totalram_pages __read_mostly;
unsigned long totalreserve_pages __read_mostly;
long nr_swap_pages;