From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753226AbcD0O52 (ORCPT ); Wed, 27 Apr 2016 10:57:28 -0400 Received: from outbound-smtp07.blacknight.com ([46.22.139.12]:38843 "EHLO outbound-smtp07.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752194AbcD0O50 (ORCPT ); Wed, 27 Apr 2016 10:57:26 -0400 From: Mel Gorman To: Andrew Morton Cc: Vlastimil Babka , Jesper Dangaard Brouer , Linux-MM , LKML , Mel Gorman Subject: [PATCH 1/6] mm, page_alloc: Only check PageCompound for high-order pages -fix Date: Wed, 27 Apr 2016 15:57:18 +0100 Message-Id: <1461769043-28337-2-git-send-email-mgorman@techsingularity.net> X-Mailer: git-send-email 2.6.4 In-Reply-To: <1461769043-28337-1-git-send-email-mgorman@techsingularity.net> References: <1461769043-28337-1-git-send-email-mgorman@techsingularity.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Vlastimil Babka pointed out that an unlikely annotation in free_pages_prepare shrinks stack usage by moving compound handling to the end of the function. add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-30 (-30) function old new delta free_pages_prepare 771 741 -30 It's also consistent with the buffered_rmqueue path. This is a fix to the mmotm patch mm-page_alloc-only-check-pagecompound-for-high-order-pages.patch. Suggested-by: Vlastimil Babka Signed-off-by: Mel Gorman --- mm/page_alloc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 1da56779f8fa..d8383750bd43 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1003,7 +1003,7 @@ static bool free_pages_prepare(struct page *page, unsigned int order) * Check tail pages before head page information is cleared to * avoid checking PageCompound for order-0 pages. */ - if (order) { + if (unlikely(order)) { bool compound = PageCompound(page); int i; -- 2.6.4