From: Yinghai Lu <yinghai@kernel.org>
Date: Wed, 11 Sep 2013 21:20:37 +0000 (-0700)
Subject: mm: kill one if loop in __free_pages_bootmem()
X-Git-Tag: upstream/snapshot3+hdmi~4342^2~250
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=e2d0bd2b924d74d5e0d4f395f8f4730d125e198c;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git

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 2748fc6..8c68ef1 100644
--- 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);
 }