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authorBob Picco <bob.picco@hp.com>2005-09-03 15:54:26 -0700
committerLinus Torvalds <torvalds@evo.osdl.org>2005-09-05 00:05:38 -0700
commit802f192e4a600f7ef84ca25c8b818c8830acef5a (patch)
tree51e9a6ed164e6a2d8741af510c3954ad79bf19af /mm/Kconfig
parent0216f86dafb389c0ad97529fd45e64e883298cfd (diff)
downloadlinux-sh-802f192e4a600f7ef84ca25c8b818c8830acef5a.tar.gz
[PATCH] SPARSEMEM EXTREME
A new option for SPARSEMEM is ARCH_SPARSEMEM_EXTREME. Architecture platforms with a very sparse physical address space would likely want to select this option. For those architecture platforms that don't select the option, the code generated is equivalent to SPARSEMEM currently in -mm. I'll be posting a patch on ia64 ml which uses this new SPARSEMEM feature. ARCH_SPARSEMEM_EXTREME makes mem_section a one dimensional array of pointers to mem_sections. This two level layout scheme is able to achieve smaller memory requirements for SPARSEMEM with the tradeoff of an additional shift and load when fetching the memory section. The current SPARSEMEM -mm implementation is a one dimensional array of mem_sections which is the default SPARSEMEM configuration. The patch attempts isolates the implementation details of the physical layout of the sparsemem section array. ARCH_SPARSEMEM_EXTREME depends on 64BIT and is by default boolean false. I've boot tested under aim load ia64 configured for ARCH_SPARSEMEM_EXTREME. I've also boot tested a 4 way Opteron machine with !ARCH_SPARSEMEM_EXTREME and tested with aim. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Bob Picco <bob.picco@hp.com> Signed-off-by: Dave Hansen <haveblue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm/Kconfig')
-rw-r--r--mm/Kconfig9
1 files changed, 9 insertions, 0 deletions
diff --git a/mm/Kconfig b/mm/Kconfig
index cd379936cac6..fc644c5c065d 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -89,3 +89,12 @@ config NEED_MULTIPLE_NODES
config HAVE_MEMORY_PRESENT
def_bool y
depends on ARCH_HAVE_MEMORY_PRESENT || SPARSEMEM
+
+#
+# Architectecture platforms which require a two level mem_section in SPARSEMEM
+# must select this option. This is usually for architecture platforms with
+# an extremely sparse physical address space.
+#
+config ARCH_SPARSEMEM_EXTREME
+ def_bool n
+ depends on SPARSEMEM && 64BIT