Against: 2.6.34-rc3-mmotm-100405-1609
Rework the generic version of the numa_node_id() function to use the
new generic percpu variable infrastructure.
Guard the new implementation with a new config option:
CONFIG_USE_PERCPU_NUMA_NODE_ID.
Archs which support this new implemention will default this option
to 'y' when NUMA is configured. This config option could be removed
if/when all archs switch over to the generic percpu implementation
of numa_node_id(). Arch support involves:
1) converting any existing per cpu variable implementations to use
this implementation. x86_64 is an instance of such an arch.
2) archs that don't use a per cpu variable for numa_node_id() will
need to initialize the new per cpu variable "numa_node" as cpus
are brought on-line. ia64 is an example.
3) Defining USE_PERCPU_NUMA_NODE_ID in arch dependent Kconfig--e.g.,
when NUMA is configured. This is required because I have
retained the old implementation by default to allow archs to
be modified incrementally, as desired.
Subsequent patches will convert x86_64 and ia64 to use this
implemenation.
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@xxxxxx>
---
V0:
# From cl@xxxxxxxxxxxxxxxxxxxx Wed Nov 4 10:36:12 2009
# Date: Wed, 4 Nov 2009 12:35:14 -0500 (EST)
# From: Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx>
# To: Lee Schermerhorn <Lee.Schermerhorn@xxxxxx>
# Subject: Re: [PATCH/RFC] slab: handle memoryless nodes efficiently
#
# I have a very early form of a draft of a patch here that genericizes
# numa_node_id(). Uses the new generic this_cpu_xxx stuff.
#
# Not complete.
V1:
+ split out x86 specific changes to subsequent patch
+ split out "numa_mem_id()" and related changes to separate patch
+ moved generic definitions of __this_cpu_xxx from linux/percpu.h
to asm-generic/percpu.h where asm/percpu.h and other asm hdrs
can use them.
+ export new percpu symbol 'numa_node' in mm/percpu.h
+ include <asm/percpu.h> in <linux/topology.h> for use by new
numa_node_id().
V2:
+ add back the #ifndef/#endif guard around numa_node_id() so that archs
can override generic definition
+ add generic stub for set_numa_node()
+ use generic percpu numa_node_id() only if enabled by
CONFIG_USE_PERCPU_NUMA_NODE_ID
to allow incremental per arch support. This option could be removed when/if
all archs that support NUMA support this option.
V3:
+ separated the rework of linux/percpu.h into another [preceding] patch.
+ moved definition of the numa_node percpu variable from mm/percpu.c to
mm/page-alloc.c
+ moved premature definition of cpu_to_mem() to later patch.
V4:
+ topology.h: include <linux/percpu.h> rather than <linux/percpu-defs.h>
Requires Tejun Heo's percpu.h/slab.h cleanup series
include/linux/topology.h | 33 ++++++++++++++++++++++++++++-----
mm/page_alloc.c | 5 +++++
2 files changed, 33 insertions(+), 5 deletions(-)
Index: linux-2.6.34-rc3-mmotm-100405-1609/mm/page_alloc.c
===================================================================
--- linux-2.6.34-rc3-mmotm-100405-1609.orig/mm/page_alloc.c 2010-04-07 10:04:04.000000000 -0400
+++ linux-2.6.34-rc3-mmotm-100405-1609/mm/page_alloc.c 2010-04-07 10:10:23.000000000 -0400
@@ -56,6 +56,11 @@
#include <asm/div64.h>
#include "internal.h"
+#ifdef CONFIG_USE_PERCPU_NUMA_NODE_ID
+DEFINE_PER_CPU(int, numa_node);
+EXPORT_PER_CPU_SYMBOL(numa_node);
+#endif
+
/*
* Array of node states.
*/
Index: linux-2.6.34-rc3-mmotm-100405-1609/include/linux/topology.h
===================================================================
--- linux-2.6.34-rc3-mmotm-100405-1609.orig/include/linux/topology.h 2010-04-07 09:49:13.000000000 -0400
+++ linux-2.6.34-rc3-mmotm-100405-1609/include/linux/topology.h 2010-04-07 10:10:23.000000000 -0400
@@ -31,6 +31,7 @@
#include <linux/bitops.h>
#include <linux/mmzone.h>
#include <linux/smp.h>
+#include <linux/percpu.h>
#include <asm/topology.h>
#ifndef node_has_online_mem
@@ -203,8 +204,35 @@ int arch_update_cpu_topology(void);
#ifndef SD_NODE_INIT
#error Please define an appropriate SD_NODE_INIT in include/asm/topology.h!!!
#endif
+
#endif /* CONFIG_NUMA */
+#ifdef CONFIG_USE_PERCPU_NUMA_NODE_ID
+DECLARE_PER_CPU(int, numa_node);
+
+#ifndef numa_node_id
+/* Returns the number of the current Node. */
+#define numa_node_id() __this_cpu_read(numa_node)
+#endif
+
+#ifndef cpu_to_node
+#define cpu_to_node(__cpu) per_cpu(numa_node, (__cpu))
+#endif
+
+#ifndef set_numa_node
+#define set_numa_node(__node) percpu_write(numa_node, __node)
+#endif
+
+#else /* !CONFIG_USE_PERCPU_NUMA_NODE_ID */
+
+/* Returns the number of the current Node. */
+#ifndef numa_node_id
+#define numa_node_id() (cpu_to_node(raw_smp_processor_id()))
+
+#endif
+
+#endif /* [!]CONFIG_USE_PERCPU_NUMA_NODE_ID */
+
#ifndef topology_physical_package_id
#define topology_physical_package_id(cpu) ((void)(cpu), -1)
#endif
@@ -218,9 +246,4 @@ int arch_update_cpu_topology(void);
#define topology_core_cpumask(cpu) cpumask_of(cpu)
#endif
-/* Returns the number of the current Node. */
-#ifndef numa_node_id
-#define numa_node_id() (cpu_to_node(raw_smp_processor_id()))
-#endif
-
#endif /* _LINUX_TOPOLOGY_H */
--
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