From 802f192e4a600f7ef84ca25c8b818c8830acef5a Mon Sep 17 00:00:00 2001 From: Bob Picco Date: Sat, 3 Sep 2005 15:54:26 -0700 Subject: [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 Signed-off-by: Bob Picco Signed-off-by: Dave Hansen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mmzone.h | 30 ++++++++++++++++++++++++++++-- 1 file changed, 28 insertions(+), 2 deletions(-) (limited to 'include/linux/mmzone.h') 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 { unsigned long section_mem_map; }; +#ifdef CONFIG_ARCH_SPARSEMEM_EXTREME +/* + * Should we ever require GCC 4 or later then the flat array scheme + * can be eliminated and a uniform solution for EXTREME and !EXTREME can + * be arrived at. + */ +#define SECTION_ROOT_SHIFT (PAGE_SHIFT-3) +#define SECTION_ROOT_MASK ((1UL<> SECTION_ROOT_SHIFT) +#define NR_SECTION_ROOTS (NR_MEM_SECTIONS >> SECTION_ROOT_SHIFT) + +extern struct mem_section *mem_section[NR_SECTION_ROOTS]; + +static inline struct mem_section *__nr_to_section(unsigned long nr) +{ + if (!mem_section[SECTION_TO_ROOT(nr)]) + return NULL; + return &mem_section[SECTION_TO_ROOT(nr)][nr & SECTION_ROOT_MASK]; +} + +#else + extern struct mem_section mem_section[NR_MEM_SECTIONS]; static 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) return &mem_section[nr]; } +#define sparse_index_init(_sec, _nid) do {} while (0) + +#endif + /* * We use the lower bits of the mem_map pointer to store * 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) static inline int valid_section(struct mem_section *section) { - return (section->section_mem_map & SECTION_MARKED_PRESENT); + return (section && (section->section_mem_map & SECTION_MARKED_PRESENT)); } static inline int section_has_mem_map(struct mem_section *section) { - return (section->section_mem_map & SECTION_HAS_MEM_MAP); + return (section && (section->section_mem_map & SECTION_HAS_MEM_MAP)); } static inline int valid_section_nr(unsigned long nr) -- cgit From 3e347261a80b57df792ab9464b5f0ed59add53a8 Mon Sep 17 00:00:00 2001 From: Bob Picco Date: Sat, 3 Sep 2005 15:54:28 -0700 Subject: [PATCH] sparsemem extreme implementation With cleanups from Dave Hansen 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 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. SPARSEMEM_EXTREME requires bootmem to be functioning at the time of memory_present() calls. This is not always feasible, so architectures which do not need it may allocate everything statically by using SPARSEMEM_STATIC. Signed-off-by: Andy Whitcroft Signed-off-by: Bob Picco Signed-off-by: Dave Hansen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mmzone.h | 40 +++++++++++++++------------------------- 1 file changed, 15 insertions(+), 25 deletions(-) (limited to 'include/linux/mmzone.h') diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index b97054bbc394..79cf578e21b9 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -487,39 +487,29 @@ struct mem_section { unsigned long section_mem_map; }; -#ifdef CONFIG_ARCH_SPARSEMEM_EXTREME -/* - * Should we ever require GCC 4 or later then the flat array scheme - * can be eliminated and a uniform solution for EXTREME and !EXTREME can - * be arrived at. - */ -#define SECTION_ROOT_SHIFT (PAGE_SHIFT-3) -#define SECTION_ROOT_MASK ((1UL<> SECTION_ROOT_SHIFT) -#define NR_SECTION_ROOTS (NR_MEM_SECTIONS >> SECTION_ROOT_SHIFT) +#ifdef CONFIG_SPARSEMEM_EXTREME +#define SECTIONS_PER_ROOT (PAGE_SIZE / sizeof (struct mem_section)) +#else +#define SECTIONS_PER_ROOT 1 +#endif -extern struct mem_section *mem_section[NR_SECTION_ROOTS]; - -static inline struct mem_section *__nr_to_section(unsigned long nr) -{ - if (!mem_section[SECTION_TO_ROOT(nr)]) - return NULL; - return &mem_section[SECTION_TO_ROOT(nr)][nr & SECTION_ROOT_MASK]; -} +#define SECTION_NR_TO_ROOT(sec) ((sec) / SECTIONS_PER_ROOT) +#define NR_SECTION_ROOTS (NR_MEM_SECTIONS / SECTIONS_PER_ROOT) +#define SECTION_ROOT_MASK (SECTIONS_PER_ROOT - 1) +#ifdef CONFIG_SPARSEMEM_EXTREME +extern struct mem_section *mem_section[NR_SECTION_ROOTS]; #else - -extern struct mem_section mem_section[NR_MEM_SECTIONS]; +extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]; +#endif static inline struct mem_section *__nr_to_section(unsigned long nr) { - return &mem_section[nr]; + if (!mem_section[SECTION_NR_TO_ROOT(nr)]) + return NULL; + return &mem_section[SECTION_NR_TO_ROOT(nr)][nr & SECTION_ROOT_MASK]; } -#define sparse_index_init(_sec, _nid) do {} while (0) - -#endif - /* * We use the lower bits of the mem_map pointer to store * a little bit of information. There should be at least -- cgit From 28ae55c98e4d16eac9a05a8a259d7763ef3aeb18 Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Sat, 3 Sep 2005 15:54:29 -0700 Subject: [PATCH] sparsemem extreme: hotplug preparation This splits up sparse_index_alloc() into two pieces. This is needed because we'll allocate the memory for the second level in a different place from where we actually consume it to keep the allocation from happening underneath a lock Signed-off-by: Dave Hansen Signed-off-by: Bob Picco Cc: Andy Whitcroft Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mmzone.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/mmzone.h') diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 79cf578e21b9..5ed471b58f4f 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -588,6 +588,7 @@ static inline int pfn_valid(unsigned long pfn) void sparse_init(void); #else #define sparse_init() do {} while (0) +#define sparse_index_init(_sec, _nid) do {} while (0) #endif /* CONFIG_SPARSEMEM */ #ifdef CONFIG_NODES_SPAN_OTHER_NODES -- cgit