mm: kill one if loop in __free_pages_bootmem()

We should not check loop+1 with loop end in loop body.  Just duplicate two
lines code to avoid it.

That will help a bit when we have huge amount of pages on system with
16TiB memory.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 2748fc6a90037f08f7946613e56987c164c0e784..8c68ef13cefa103bbd4136399dad6522bba76f4e 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -751,19 +751,19 @@ static void __free_pages_ok(struct page *page, unsigned int order)
 void __init __free_pages_bootmem(struct page *page, unsigned int order)
 {
        unsigned int nr_pages = 1 << order;
+       struct page *p = page;
        unsigned int loop;
 
-       prefetchw(page);
-       for (loop = 0; loop < nr_pages; loop++) {
-               struct page *p = &page[loop];
-
-               if (loop + 1 < nr_pages)
-                       prefetchw(p + 1);
+       prefetchw(p);
+       for (loop = 0; loop < (nr_pages - 1); loop++, p++) {
+               prefetchw(p + 1);
                __ClearPageReserved(p);
                set_page_count(p, 0);
        }
+       __ClearPageReserved(p);
+       set_page_count(p, 0);
 
-       page_zone(page)->managed_pages += 1 << order;
+       page_zone(page)->managed_pages += nr_pages;
        set_page_refcounted(page);
        __free_pages(page, order);
 }