[PATCH] flatmem split out memory model
There are three places we define pfn_to_nid(). Two in linux/mmzone.h and one
in asm/mmzone.h. These in essence represent the three memory models. The
definition in linux/mmzone.h under !NEED_MULTIPLE_NODES is both the FLATMEM
definition and the optimisation for single NUMA nodes; the one under SPARSEMEM
is the NUMA sparsemem one; the one in asm/mmzone.h under DISCONTIGMEM is the
discontigmem one. This is not in the least bit obvious, particularly the
connection between the non-NUMA optimisations and the memory models.
Two patches:
flatmem-split-out-memory-model: simplifies the selection of pfn_to_nid()
implementations. The selection is based primarily off the memory model
selected. Optimisations for non-NUMA are applied where needed.
sparse-provide-pfn_to_nid: implement pfn_to_nid() for SPARSEMEM
This patch:
pfn_to_nid is memory model specific
The pfn_to_nid() call is memory model specific. It represents the locality
identifier for the memory passed. Classically this would be a NUMA node,
but not a chunk of memory under DISCONTIGMEM.
The SPARSEMEM and FLATMEM memory model non-NUMA versions of pfn_to_nid()
are folded together under NEED_MULTIPLE_NODES, while DISCONTIGMEM has its
own optimisation. This is all very confusing.
This patch splits out each implementation of pfn_to_nid() so that we can
see them and the optimisations to each.
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index d294b57..ee9f7b7 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -435,7 +435,6 @@
#define NODE_DATA(nid) (&contig_page_data)
#define NODE_MEM_MAP(nid) mem_map
#define MAX_NODES_SHIFT 1
-#define pfn_to_nid(pfn) (0)
#else /* CONFIG_NEED_MULTIPLE_NODES */
@@ -470,6 +469,10 @@
#define early_pfn_to_nid(nid) (0UL)
#endif
+#ifdef CONFIG_FLATMEM
+#define pfn_to_nid(pfn) (0)
+#endif
+
#define pfn_to_section_nr(pfn) ((pfn) >> PFN_SECTION_SHIFT)
#define section_nr_to_pfn(sec) ((sec) << PFN_SECTION_SHIFT)
@@ -594,6 +597,8 @@
*/
#ifdef CONFIG_NUMA
#define pfn_to_nid early_pfn_to_nid
+#else
+#define pfn_to_nid(pfn) (0)
#endif
#define early_pfn_valid(pfn) pfn_valid(pfn)