Incremental patch 2 to
numa-introduce-numa_mem_id-effective-local-memory-node-id
in 28april10 mmotm.
Remove the "#define numa_mem numa_node" when !HAVE_MEMORYLESS_NODES
from topology.h per Tejun Heo. Because 'numa_mem' is [was] a percpu
variable, we cannot make it a macro with arguments or a static inline
function. I considered making it a variable alias for numa_node, but
since both are percpu variables whose actual definitions and declarations
are buried deep in the DECLARE_PER_CPU() macros, I proposed a
DECLARE_PER_CPU_ALIAS(variable, alias). Tejun agreed that if this
were a common occurrence, that would be a good idea, but since we
currently have only this instance, we agreed to just eliminate
the numa_mem variable when !HAVE_MEMORYLESS_NODES.
This patch renames the variable to _numa_mem_ and adds warnings
in both linux/topology.h and mm/page_alloc.c against referencing
the variable directly. The accessor functions numa_mem_id() and
cpu_to_mem() will return the appropriate value when
!HAVE_MEMORYLESS_NODES.
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@xxxxxx>
include/linux/topology.h | 35 +++++++++++++++++++++++++++--------
mm/page_alloc.c | 10 ++++++++--
2 files changed, 35 insertions(+), 10 deletions(-)
Index: linux-2.6.34-rc5-mmotm-100428-1653/include/linux/topology.h
===================================================================
--- linux-2.6.34-rc5-mmotm-100428-1653.orig/include/linux/topology.h
+++ linux-2.6.34-rc5-mmotm-100428-1653/include/linux/topology.h
@@ -253,46 +253,65 @@ static inline int numa_node_id(void)
#ifdef CONFIG_HAVE_MEMORYLESS_NODES
-DECLARE_PER_CPU(int, numa_mem);
+/*
+ * N.B., Do NOT reference the '_numa_mem_' per cpu variable directly.
+ * It will not be defined when CONFIG_HAVE_MEMORYLESS_NODES is not defined.
+ * Use the accessor functions set_numa_mem(), numa_mem_id() and cpu_to_mem().
+ */
+DECLARE_PER_CPU(int, _numa_mem_);
#ifndef set_numa_mem
static inline void set_numa_mem(int node)
{
- percpu_write(numa_mem, node);
+ percpu_write(_numa_mem_, node);
+}
+#endif
+
+#ifndef numa_mem_id
+/* Returns the number of the nearest Node with memory */
+static inline int numa_mem_id(void)
+{
+ return __this_cpu_read(_numa_mem_);
+}
+#endif
+
+#ifndef cpu_to_mem
+static inline int cpu_to_mem(int cpu)
+{
+ return per_cpu(_numa_mem_, cpu);
}
#endif
#ifndef set_cpu_numa_mem
static inline void set_cpu_numa_mem(int cpu, int node)
{
- per_cpu(numa_mem, cpu) = node;
+ per_cpu(_numa_mem_, cpu) = node;
}
#endif
#else /* !CONFIG_HAVE_MEMORYLESS_NODES */
-#define numa_mem numa_node
static inline void set_numa_mem(int node) {}
static inline void set_cpu_numa_mem(int cpu, int node) {}
-#endif /* [!]CONFIG_HAVE_MEMORYLESS_NODES */
-
#ifndef numa_mem_id
/* Returns the number of the nearest Node with memory */
static inline int numa_mem_id(void)
{
- return __this_cpu_read(numa_mem);
+ return numa_node_id();
}
#endif
#ifndef cpu_to_mem
static inline int cpu_to_mem(int cpu)
{
- return per_cpu(numa_mem, cpu);
+ return cpu_to_node(cpu);
}
#endif
+#endif /* [!]CONFIG_HAVE_MEMORYLESS_NODES */
+
#ifndef topology_physical_package_id
#define topology_physical_package_id(cpu) ((void)(cpu), -1)
#endif
Index: linux-2.6.34-rc5-mmotm-100428-1653/mm/page_alloc.c
===================================================================
--- linux-2.6.34-rc5-mmotm-100428-1653.orig/mm/page_alloc.c
+++ linux-2.6.34-rc5-mmotm-100428-1653/mm/page_alloc.c
@@ -63,8 +63,14 @@ EXPORT_PER_CPU_SYMBOL(numa_node);
#endif
#ifdef CONFIG_HAVE_MEMORYLESS_NODES
-DEFINE_PER_CPU(int, numa_mem); /* Kernel "local memory" node */
-EXPORT_PER_CPU_SYMBOL(numa_mem);
+/*
+ * N.B., Do NOT reference the '_numa_mem_' per cpu variable directly.
+ * It will not be defined when CONFIG_HAVE_MEMORYLESS_NODES is not defined.
+ * Use the accessor functions set_numa_mem(), numa_mem_id() and cpu_to_mem()
+ * defined in <linux/topology.h>.
+ */
+DEFINE_PER_CPU(int, _numa_mem_); /* Kernel "local memory" node */
+EXPORT_PER_CPU_SYMBOL(_numa_mem_);
#endif
/*
--
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