From: Zhou Chengming <zhouchengming1@xxxxxxxxxx> Subject: make __section_nr() more efficient When CONFIG_SPARSEMEM_EXTREME is disabled, __section_nr can get the section number with a subtraction directly. Link: http://lkml.kernel.org/r/1468988310-11560-1-git-send-email-zhouchengming1@xxxxxxxxxx Signed-off-by: Zhou Chengming <zhouchengming1@xxxxxxxxxx> Cc: Dave Hansen <dave.hansen@xxxxxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Cc: Hanjun Guo <guohanjun@xxxxxxxxxx> Cc: Li Bin <huawei.libin@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/sparse.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff -puN mm/sparse.c~make-__section_nr-more-efficient mm/sparse.c --- a/mm/sparse.c~make-__section_nr-more-efficient +++ a/mm/sparse.c @@ -100,11 +100,7 @@ static inline int sparse_index_init(unsi } #endif -/* - * Although written for the SPARSEMEM_EXTREME case, this happens - * to also work for the flat array case because - * NR_SECTION_ROOTS==NR_MEM_SECTIONS. - */ +#ifdef CONFIG_SPARSEMEM_EXTREME int __section_nr(struct mem_section* ms) { unsigned long root_nr; @@ -123,6 +119,12 @@ int __section_nr(struct mem_section* ms) return (root_nr * SECTIONS_PER_ROOT) + (ms - root); } +#else +int __section_nr(struct mem_section* ms) +{ + return (int)(ms - mem_section[0]); +} +#endif /* * During early boot, before section_mem_map is used for an actual _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
