From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932379AbbIUKyz (ORCPT ); Mon, 21 Sep 2015 06:54:55 -0400 Received: from outbound-smtp02.blacknight.com ([81.17.249.8]:55914 "EHLO outbound-smtp02.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932212AbbIUKwp (ORCPT ); Mon, 21 Sep 2015 06:52:45 -0400 From: Mel Gorman To: Andrew Morton Cc: Johannes Weiner , Rik van Riel , Vlastimil Babka , David Rientjes , Joonsoo Kim , Michal Hocko , Linux-MM , LKML , Mel Gorman Subject: [PATCH 03/10] mm, page_alloc: Remove unnecessary taking of a seqlock when cpusets are disabled Date: Mon, 21 Sep 2015 11:52:35 +0100 Message-Id: <1442832762-7247-4-git-send-email-mgorman@techsingularity.net> X-Mailer: git-send-email 2.4.6 In-Reply-To: <1442832762-7247-1-git-send-email-mgorman@techsingularity.net> References: <1442832762-7247-1-git-send-email-mgorman@techsingularity.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There is a seqcounter that protects against spurious allocation failures when a task is changing the allowed nodes in a cpuset. There is no need to check the seqcounter until a cpuset exists. Signed-off-by: Mel Gorman Acked-by: Christoph Lameter Acked-by: David Rientjes Acked-by: Vlastimil Babka Acked-by: Michal Hocko --- include/linux/cpuset.h | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h index 1b357997cac5..6eb27cb480b7 100644 --- a/include/linux/cpuset.h +++ b/include/linux/cpuset.h @@ -104,6 +104,9 @@ extern void cpuset_print_task_mems_allowed(struct task_struct *p); */ static inline unsigned int read_mems_allowed_begin(void) { + if (!cpusets_enabled()) + return 0; + return read_seqcount_begin(¤t->mems_allowed_seq); } @@ -115,6 +118,9 @@ static inline unsigned int read_mems_allowed_begin(void) */ static inline bool read_mems_allowed_retry(unsigned int seq) { + if (!cpusets_enabled()) + return false; + return read_seqcount_retry(¤t->mems_allowed_seq, seq); } -- 2.4.6