Messages in this thread Patch in this message | | | Date | Mon, 03 Mar 2008 16:04:58 -0800 | From | Christoph Lameter <> | Subject | [rfc 06/10] Sparsemem: Vmemmap does not need section bits |
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Sparsemem vmemmap does not need any section bits. This patch has the effect of reducing the number of bits used in page->flags by at least 6.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
--- include/linux/mm.h | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
Index: linux-2.6/include/linux/mm.h =================================================================== --- linux-2.6.orig/include/linux/mm.h 2008-03-03 15:45:07.047305876 -0800 +++ linux-2.6/include/linux/mm.h 2008-03-03 15:49:04.686432973 -0800 @@ -390,11 +390,11 @@ static inline void set_compound_order(st * we have run out of space and have to fall back to an * alternate (slower) way of determining the node. * - * No sparsemem: | NODE | ZONE | ... | FLAGS | - * with space for node: | SECTION | NODE | ZONE | ... | FLAGS | - * no space for node: | SECTION | ZONE | ... | FLAGS | + * No sparsemem or sparsemem vmemmap: | NODE | ZONE | ... | FLAGS | + * classic sparse with space for node:| SECTION | NODE | ZONE | ... | FLAGS | + * classic sparse no space for node: | SECTION | ZONE | ... | FLAGS | */ -#ifdef CONFIG_SPARSEMEM +#if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP) #define SECTIONS_WIDTH SECTIONS_SHIFT #else #define SECTIONS_WIDTH 0 @@ -405,6 +405,9 @@ static inline void set_compound_order(st #if SECTIONS_WIDTH+ZONES_WIDTH+NODES_SHIFT <= FLAGS_RESERVED #define NODES_WIDTH NODES_SHIFT #else +#ifdef CONFIG_SPARSEMEM_VMEMMAP +#error "Vmemmap: No space for nodes field in page flags" +#endif #define NODES_WIDTH 0 #endif --
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