From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933621Ab3CHXQv (ORCPT ); Fri, 8 Mar 2013 18:16:51 -0500 Received: from mail-gh0-f174.google.com ([209.85.160.174]:56033 "EHLO mail-gh0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932697Ab3CHXQt (ORCPT ); Fri, 8 Mar 2013 18:16:49 -0500 From: "Raphael S.Carvalho" To: "David S. Miller" , Serge Hallyn , "Serge E. Hallyn" , Andrew Morton , "Eric W. Biederman" Cc: linux-kernel@vger.kernel.org, "Raphael S.Carvalho" Subject: [PATCH 1/1] kernel/pid.c: Improve flow of a loop inside alloc_pidmap. Date: Fri, 8 Mar 2013 20:07:47 -0300 Message-Id: <1362784067-15537-1-git-send-email-raphael.scarv@gmail.com> X-Mailer: git-send-email 1.7.2.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Notes: find_next_offset searches for an available "cleaned bit" in the respective pid bitmap (page), so returns the offset if found, otherwise it returns a value equals to BITS_PER_PAGE (invalid offset). For example, suppose find_next_offset didn't find any available bit, so there's no purpose to call mk_pid (Wasteful Cpu Cycles) since it only computes a new PID based on a *valid* offset of the current map. Therefore, I found it could be better to call mk_pid after the checking (offset < BITS_PER_PAGE) returned sucessfully! Signed-off-by: Raphael S.Carvalho --- kernel/pid.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/pid.c b/kernel/pid.c index 047dc62..7ecb09a 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -190,8 +190,8 @@ static int alloc_pidmap(struct pid_namespace *pid_ns) return pid; } offset = find_next_offset(map, offset); - pid = mk_pid(pid_ns, map, offset); - } while (offset < BITS_PER_PAGE && pid < pid_max); + } while (offset < BITS_PER_PAGE && + (pid = mk_pid(pid_ns, map, offset)) < pid_max); } if (map < &pid_ns->pidmap[(pid_max-1)/BITS_PER_PAGE]) { ++map; -- 1.7.2.5