From: Fernando Luis Vazquez Cao Date: Thu, 8 Jan 2009 02:07:51 +0000 (-0800) Subject: memcg: do not recalculate section unnecessarily in init_section_page_cgroup X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=0753b0ef3b301895234fed02bea2c099c7ff4feb;p=linux-beck.git memcg: do not recalculate section unnecessarily in init_section_page_cgroup In init_section_page_cgroup() the section a given pfn belongs to is calculated at the top of the function and, despite the fact that the pfn/section correspondence does not change, it is recalculated further down the same function. By computing this just once and reusing that value we save some bytes in the object file and do not waste CPU cycles. Signed-off-by: Fernando Luis Vazquez Cao Reviewed-by: KAMEZAWA Hiroyuki Cc: Daisuke Nishimura Cc: Balbir Singh Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c index d6507a660ed6..df1e54a5ed19 100644 --- a/mm/page_cgroup.c +++ b/mm/page_cgroup.c @@ -103,13 +103,11 @@ struct page_cgroup *lookup_page_cgroup(struct page *page) /* __alloc_bootmem...() is protected by !slab_available() */ static int __init_refok init_section_page_cgroup(unsigned long pfn) { - struct mem_section *section; + struct mem_section *section = __pfn_to_section(pfn); struct page_cgroup *base, *pc; unsigned long table_size; int nid, index; - section = __pfn_to_section(pfn); - if (!section->page_cgroup) { nid = page_to_nid(pfn_to_page(pfn)); table_size = sizeof(struct page_cgroup) * PAGES_PER_SECTION; @@ -145,7 +143,6 @@ static int __init_refok init_section_page_cgroup(unsigned long pfn) __init_page_cgroup(pc, pfn + index); } - section = __pfn_to_section(pfn); section->page_cgroup = base - pfn; total_usage += table_size; return 0;