make __section_nr() more efficient (91fd8b95) · Commits · 戴 / test

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@huawei.com Signed-off-by:

Zhou Chengming <zhouchengming1@huawei.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Tejun Heo <tj@kernel.org> Cc: Hanjun Guo <guohanjun@huawei.com> Cc: Li Bin <huawei.libin@huawei.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

mm/sparse.c

+7 −5

Original line number	Diff line number	Diff line
		@@ -100,11 +100,7 @@ static inline int sparse_index_init(unsigned long section_nr, int nid)
		}
		#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

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