Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759594Ab3FDGwz (ORCPT ); Tue, 4 Jun 2013 02:52:55 -0400 Received: from mail-lb0-f170.google.com ([209.85.217.170]:38321 "EHLO mail-lb0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759292Ab3FDGww (ORCPT ); Tue, 4 Jun 2013 02:52:52 -0400 MIME-Version: 1.0 In-Reply-To: <51AD87D0.7020300@linux.vnet.ibm.com> References: <51AD87A8.6080608@linux.vnet.ibm.com> <51AD87D0.7020300@linux.vnet.ibm.com> From: Paul Turner Date: Mon, 3 Jun 2013 23:52:20 -0700 Message-ID: Subject: Re: [PATCH 1/3] sched: don't repeat the initialization in sched_init() To: Michael Wang Cc: LKML , Peter Zijlstra , Ingo Molnar Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4142 Lines: 95 On Mon, Jun 3, 2013 at 11:23 PM, Michael Wang wrote: > In sched_init(), there is no need to initialize 'root_task_group.shares' and > 'root_task_group.cfs_bandwidth' repeatedly. > > CC: Ingo Molnar > CC: Peter Zijlstra > Signed-off-by: Michael Wang > --- > kernel/sched/core.c | 46 +++++++++++++++++++++++++--------------------- > 1 files changed, 25 insertions(+), 21 deletions(-) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 58453b8..c0c3716 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -6955,6 +6955,31 @@ void __init sched_init(void) > > #endif /* CONFIG_CGROUP_SCHED */ > > +#ifdef CONFIG_FAIR_GROUP_SCHED > + root_task_group.shares = ROOT_TASK_GROUP_LOAD; > + > + /* > + * How much cpu bandwidth does root_task_group get? > + * > + * In case of task-groups formed thr' the cgroup filesystem, it > + * gets 100% of the cpu resources in the system. This overall > + * system cpu resource is divided among the tasks of > + * root_task_group and its child task-groups in a fair manner, > + * based on each entity's (task or task-group's) weight > + * (se->load.weight). > + * > + * In other words, if root_task_group has 10 tasks of weight > + * 1024) and two child groups A0 and A1 (of weight 1024 each), > + * then A0's share of the cpu resource is: > + * > + * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33% > + * > + * We achieve this by letting root_task_group's tasks sit > + * directly in rq->cfs (i.e root_task_group->se[] = NULL). > + */ This comment has become unglued from what it's supposed to be attached to (it's tied to root_task_group.shares & init_tg_cfs_entry, not init_cfs_bandwidth). > + init_cfs_bandwidth(&root_task_group.cfs_bandwidth); > +#endif > + > for_each_possible_cpu(i) { > struct rq *rq; > > @@ -6966,28 +6991,7 @@ void __init sched_init(void) > init_cfs_rq(&rq->cfs); > init_rt_rq(&rq->rt, rq); > #ifdef CONFIG_FAIR_GROUP_SCHED > - root_task_group.shares = ROOT_TASK_GROUP_LOAD; > INIT_LIST_HEAD(&rq->leaf_cfs_rq_list); > - /* > - * How much cpu bandwidth does root_task_group get? > - * > - * In case of task-groups formed thr' the cgroup filesystem, it > - * gets 100% of the cpu resources in the system. This overall > - * system cpu resource is divided among the tasks of > - * root_task_group and its child task-groups in a fair manner, > - * based on each entity's (task or task-group's) weight > - * (se->load.weight). > - * > - * In other words, if root_task_group has 10 tasks of weight > - * 1024) and two child groups A0 and A1 (of weight 1024 each), > - * then A0's share of the cpu resource is: > - * > - * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33% > - * > - * We achieve this by letting root_task_group's tasks sit > - * directly in rq->cfs (i.e root_task_group->se[] = NULL). > - */ > - init_cfs_bandwidth(&root_task_group.cfs_bandwidth); > init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL); > #endif /* CONFIG_FAIR_GROUP_SCHED */ > > -- > 1.7.4.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/