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authorBob Picco <bob.picco@hp.com>2005-09-03 18:54:26 -0400
committerLinus Torvalds <torvalds@evo.osdl.org>2005-09-05 03:05:38 -0400
commit802f192e4a600f7ef84ca25c8b818c8830acef5a (patch)
tree51e9a6ed164e6a2d8741af510c3954ad79bf19af /include/linux/mmzone.h
parent0216f86dafb389c0ad97529fd45e64e883298cfd (diff)
[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 'include/linux/mmzone.h')
-rw-r--r--include/linux/mmzone.h30
1 files changed, 28 insertions, 2 deletions
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 6c90461ed99f..b97054bbc394 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -487,6 +487,28 @@ struct mem_section {
487 unsigned long section_mem_map; 487 unsigned long section_mem_map;
488}; 488};
489 489
490#ifdef CONFIG_ARCH_SPARSEMEM_EXTREME
491/*
492 * Should we ever require GCC 4 or later then the flat array scheme
493 * can be eliminated and a uniform solution for EXTREME and !EXTREME can
494 * be arrived at.
495 */
496#define SECTION_ROOT_SHIFT (PAGE_SHIFT-3)
497#define SECTION_ROOT_MASK ((1UL<<SECTION_ROOT_SHIFT) - 1)
498#define SECTION_TO_ROOT(_sec) ((_sec) >> SECTION_ROOT_SHIFT)
499#define NR_SECTION_ROOTS (NR_MEM_SECTIONS >> SECTION_ROOT_SHIFT)
500
501extern struct mem_section *mem_section[NR_SECTION_ROOTS];
502
503static inline struct mem_section *__nr_to_section(unsigned long nr)
504{
505 if (!mem_section[SECTION_TO_ROOT(nr)])
506 return NULL;
507 return &mem_section[SECTION_TO_ROOT(nr)][nr & SECTION_ROOT_MASK];
508}
509
510#else
511
490extern struct mem_section mem_section[NR_MEM_SECTIONS]; 512extern struct mem_section mem_section[NR_MEM_SECTIONS];
491 513
492static inline struct mem_section *__nr_to_section(unsigned long nr) 514static inline struct mem_section *__nr_to_section(unsigned long nr)
@@ -494,6 +516,10 @@ static inline struct mem_section *__nr_to_section(unsigned long nr)
494 return &mem_section[nr]; 516 return &mem_section[nr];
495} 517}
496 518
519#define sparse_index_init(_sec, _nid) do {} while (0)
520
521#endif
522
497/* 523/*
498 * We use the lower bits of the mem_map pointer to store 524 * We use the lower bits of the mem_map pointer to store
499 * a little bit of information. There should be at least 525 * a little bit of information. There should be at least
@@ -513,12 +539,12 @@ static inline struct page *__section_mem_map_addr(struct mem_section *section)
513 539
514static inline int valid_section(struct mem_section *section) 540static inline int valid_section(struct mem_section *section)
515{ 541{
516 return (section->section_mem_map & SECTION_MARKED_PRESENT); 542 return (section && (section->section_mem_map & SECTION_MARKED_PRESENT));
517} 543}
518 544
519static inline int section_has_mem_map(struct mem_section *section) 545static inline int section_has_mem_map(struct mem_section *section)
520{ 546{
521 return (section->section_mem_map & SECTION_HAS_MEM_MAP); 547 return (section && (section->section_mem_map & SECTION_HAS_MEM_MAP));
522} 548}
523 549
524static inline int valid_section_nr(unsigned long nr) 550static inline int valid_section_nr(unsigned long nr)