From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754748Ab2GXORS (ORCPT ); Tue, 24 Jul 2012 10:17:18 -0400 Received: from terminus.zytor.com ([198.137.202.10]:41998 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754450Ab2GXORR (ORCPT ); Tue, 24 Jul 2012 10:17:17 -0400 Date: Tue, 24 Jul 2012 07:15:41 -0700 From: "tip-bot for Srivatsa S. Bhat" Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, torvalds@linux-foundation.org, a.p.zijlstra@chello.nl, srivatsa.bhat@linux.vnet.ibm.com, akpm@linux-foundation.org, tglx@linutronix.de Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl, torvalds@linux-foundation.org, srivatsa.bhat@linux.vnet.ibm.com, akpm@linux-foundation.org, tglx@linutronix.de In-Reply-To: <20120524141635.3692.893.stgit@srivatsabhat.in.ibm.com> References: <20120524141635.3692.893.stgit@srivatsabhat.in.ibm.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] cpusets, hotplug: Implement cpuset tree traversal in a helper function Git-Commit-ID: 80d1fa6463d934969b7aebf04107fc133463f0f6 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.6 (terminus.zytor.com [127.0.0.1]); Tue, 24 Jul 2012 07:15:49 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 80d1fa6463d934969b7aebf04107fc133463f0f6 Gitweb: http://git.kernel.org/tip/80d1fa6463d934969b7aebf04107fc133463f0f6 Author: Srivatsa S. Bhat AuthorDate: Thu, 24 May 2012 19:46:41 +0530 Committer: Ingo Molnar CommitDate: Tue, 24 Jul 2012 13:53:18 +0200 cpusets, hotplug: Implement cpuset tree traversal in a helper function At present, the functions that deal with cpusets during CPU/Mem hotplug are quite messy, since a lot of the functionality is mixed up without clear separation. And this takes a toll on optimization as well. For example, the function cpuset_update_active_cpus() is called on both CPU offline and CPU online events; and it invokes scan_for_empty_cpusets(), which makes sense only for CPU offline events. And hence, the current code ends up unnecessarily traversing the cpuset tree during CPU online also. As a first step towards cleaning up those functions, encapsulate the cpuset tree traversal in a helper function, so as to facilitate upcoming changes. Signed-off-by: Srivatsa S. Bhat Signed-off-by: Peter Zijlstra Cc: Linus Torvalds Cc: Andrew Morton Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20120524141635.3692.893.stgit@srivatsabhat.in.ibm.com Signed-off-by: Ingo Molnar --- kernel/cpuset.c | 36 +++++++++++++++++++++++++++--------- 1 files changed, 27 insertions(+), 9 deletions(-) diff --git a/kernel/cpuset.c b/kernel/cpuset.c index 746d1ee..ba96349 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -1990,6 +1990,32 @@ static void remove_tasks_in_empty_cpuset(struct cpuset *cs) } /* + * Helper function to traverse cpusets. + * It can be used to walk the cpuset tree from top to bottom, completing + * one layer before dropping down to the next (thus always processing a + * node before any of its children). + */ +static struct cpuset *cpuset_next(struct list_head *queue) +{ + struct cpuset *cp; + struct cpuset *child; /* scans child cpusets of cp */ + struct cgroup *cont; + + if (list_empty(queue)) + return NULL; + + cp = list_first_entry(queue, struct cpuset, stack_list); + list_del(queue->next); + list_for_each_entry(cont, &cp->css.cgroup->children, sibling) { + child = cgroup_cs(cont); + list_add_tail(&child->stack_list, queue); + } + + return cp; +} + + +/* * Walk the specified cpuset subtree and look for empty cpusets. * The tasks of such cpuset must be moved to a parent cpuset. * @@ -2008,19 +2034,11 @@ static void scan_for_empty_cpusets(struct cpuset *root) { LIST_HEAD(queue); struct cpuset *cp; /* scans cpusets being updated */ - struct cpuset *child; /* scans child cpusets of cp */ - struct cgroup *cont; static nodemask_t oldmems; /* protected by cgroup_mutex */ list_add_tail((struct list_head *)&root->stack_list, &queue); - while (!list_empty(&queue)) { - cp = list_first_entry(&queue, struct cpuset, stack_list); - list_del(queue.next); - list_for_each_entry(cont, &cp->css.cgroup->children, sibling) { - child = cgroup_cs(cont); - list_add_tail(&child->stack_list, &queue); - } + while ((cp = cpuset_next(&queue)) != NULL) { /* Continue past cpusets with all cpus, mems online */ if (cpumask_subset(cp->cpus_allowed, cpu_active_mask) &&