From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754040AbdKFQGY (ORCPT ); Mon, 6 Nov 2017 11:06:24 -0500 Received: from merlin.infradead.org ([205.233.59.134]:45300 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753845AbdKFQGX (ORCPT ); Mon, 6 Nov 2017 11:06:23 -0500 Date: Mon, 6 Nov 2017 17:06:21 +0100 From: Peter Zijlstra To: Kirill Tkhai Cc: mingo@redhat.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/4] sched: Account per task_group nr_iowait Message-ID: <20171106160621.GK3165@worktop.lehotels.local> References: <150997831079.4082.2128628793286090861.stgit@localhost.localdomain> <150997923220.4082.7025655919924328239.stgit@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <150997923220.4082.7025655919924328239.stgit@localhost.localdomain> User-Agent: Mutt/1.5.22.1 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 06, 2017 at 05:40:32PM +0300, Kirill Tkhai wrote: > The patch makes number of task_group's tasks in iowait state > be tracked separately. This may be useful for containers to > check nr_iowait state of a single one. > > Signed-off-by: Kirill Tkhai > --- > kernel/sched/core.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ > kernel/sched/sched.h | 5 +++++ > 2 files changed, 50 insertions(+) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 712ee54edaa1..86d1ad5f49bd 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -796,12 +796,32 @@ void deactivate_task(struct rq *rq, struct task_struct *p, int flags) > > static void task_iowait_start(struct rq *rq, struct task_struct *p) > { > +#ifdef CONFIG_CGROUP_SCHED > + struct task_group *tg = task_group(p); > + > + /* Task's sched_task_group is changed under both of the below locks */ > + BUG_ON(!raw_spin_is_locked(&p->pi_lock) && !raw_spin_is_locked(&rq->lock)); We have lockdep_assert_held for that. > + while (task_group_is_autogroup(tg)) > + tg = tg->parent; > + atomic_inc(&tg->stat[rq->cpu].nr_iowait); You're joking right, more atomic ops on the fast paths.. > +#endif > + > atomic_inc(&rq->nr_iowait); > delayacct_blkio_start();