During the sparse_init(), it iterate on each possible section. On x86_64, it would always be (2^19) even there is not much memory. For example, on a typical 4G machine, it has only (2^5) to (2^6) present sections. This benefits more on a system with smaller memory.
This patch calculates the last section number from the highest pfn and use this as the boundary of iteration. Signed-off-by: Wei Yang <[email protected]> --- mm/sparse.c | 32 +++++++++++++++++++++----------- 1 file changed, 21 insertions(+), 11 deletions(-) diff --git a/mm/sparse.c b/mm/sparse.c index 1e168bf2779a..d72f390d9e61 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -468,18 +468,20 @@ void __weak __meminit vmemmap_populate_print_last(void) /** * alloc_usemap_and_memmap - memory alloction for pageblock flags and vmemmap - * @map: usemap_map for pageblock flags or mmap_map for vmemmap + * @data: usemap_map for pageblock flags or mmap_map for vmemmap */ static void __init alloc_usemap_and_memmap(void (*alloc_func) (void *, unsigned long, unsigned long, - unsigned long, int), void *data) + unsigned long, int), + void *data, + unsigned long last_section_nr) { unsigned long pnum; unsigned long map_count; int nodeid_begin = 0; unsigned long pnum_begin = 0; - for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) { + for (pnum = 0; pnum <= last_section_nr; pnum++) { struct mem_section *ms; if (!present_section_nr(pnum)) @@ -490,7 +492,7 @@ static void __init alloc_usemap_and_memmap(void (*alloc_func) break; } map_count = 1; - for (pnum = pnum_begin + 1; pnum < NR_MEM_SECTIONS; pnum++) { + for (pnum = pnum_begin + 1; pnum <= last_section_nr; pnum++) { struct mem_section *ms; int nodeid; @@ -503,16 +505,14 @@ static void __init alloc_usemap_and_memmap(void (*alloc_func) continue; } /* ok, we need to take cake of from pnum_begin to pnum - 1*/ - alloc_func(data, pnum_begin, pnum, - map_count, nodeid_begin); + alloc_func(data, pnum_begin, pnum, map_count, nodeid_begin); /* new start, update count etc*/ nodeid_begin = nodeid; pnum_begin = pnum; map_count = 1; } /* ok, last chunk */ - alloc_func(data, pnum_begin, NR_MEM_SECTIONS, - map_count, nodeid_begin); + alloc_func(data, pnum_begin, pnum, map_count, nodeid_begin); } /* @@ -526,6 +526,9 @@ void __init sparse_init(void) unsigned long *usemap; unsigned long **usemap_map; int size; + unsigned long last_section_nr; + int i; + unsigned long last_pfn = 0; #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER int size2; struct page **map_map; @@ -537,6 +540,11 @@ void __init sparse_init(void) /* Setup pageblock_order for HUGETLB_PAGE_SIZE_VARIABLE */ set_pageblock_order(); + for_each_mem_pfn_range_rev(i, NUMA_NO_NODE, NULL, + &last_pfn, NULL) + break; + last_section_nr = pfn_to_section_nr(last_pfn); + /* * map is using big page (aka 2M in x86 64 bit) * usemap is less one page (aka 24 bytes) @@ -553,7 +561,8 @@ void __init sparse_init(void) if (!usemap_map) panic("can not allocate usemap_map\n"); alloc_usemap_and_memmap(sparse_early_usemaps_alloc_node, - (void *)usemap_map); + (void *)usemap_map, + last_section_nr); #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER size2 = sizeof(struct page *) * NR_MEM_SECTIONS; @@ -561,10 +570,11 @@ void __init sparse_init(void) if (!map_map) panic("can not allocate map_map\n"); alloc_usemap_and_memmap(sparse_early_mem_maps_alloc_node, - (void *)map_map); + (void *)map_map, + last_section_nr); #endif - for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) { + for (pnum = 0; pnum <= last_section_nr; pnum++) { if (!present_section_nr(pnum)) continue; -- 2.11.0
