From mboxrd@z Thu Jan 1 00:00:00 1970 From: Waiman Long Subject: [PATCH v11 3/9] cpuset: Simulate auto-off of sched.partition at cgroup removal Date: Sun, 24 Jun 2018 15:30:34 +0800 Message-ID: <1529825440-9574-4-git-send-email-longman@redhat.com> References: <1529825440-9574-1-git-send-email-longman@redhat.com> Return-path: In-Reply-To: <1529825440-9574-1-git-send-email-longman@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Tejun Heo , Li Zefan , Johannes Weiner , Peter Zijlstra , Ingo Molnar Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, kernel-team@fb.com, pjt@google.com, luto@amacapital.net, Mike Galbraith , torvalds@linux-foundation.org, Roman Gushchin , Juri Lelli , Patrick Bellasi , Waiman Long Making a cgroup a partition root will reserve cpu resource at its parent. So when a partition root cgroup is destroyed, we need to free the reserved cpus at its parent. This is now done by doing an auto-off of the sched.partition flag in the offlining phase when a partition root cgroup is being removed. Signed-off-by: Waiman Long --- kernel/cgroup/cpuset.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 5989bff..e902f54 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -2278,7 +2278,12 @@ static int cpuset_css_online(struct cgroup_subsys_state *css) /* * If the cpuset being removed has its flag 'sched_load_balance' * enabled, then simulate turning sched_load_balance off, which - * will call rebuild_sched_domains_locked(). + * will call rebuild_sched_domains_locked(). That is not needed + * in the default hierarchy where only changes in partition + * will cause repartitioning. + * + * If the cpuset has the 'sched.partition' flag enabled, simulate + * turning 'sched.partition" off. */ static void cpuset_css_offline(struct cgroup_subsys_state *css) @@ -2287,7 +2292,18 @@ static void cpuset_css_offline(struct cgroup_subsys_state *css) mutex_lock(&cpuset_mutex); - if (is_sched_load_balance(cs)) + /* + * A WARN_ON_ONCE() check after calling update_flag() to make + * sure that the operation succceeds without failure. + */ + if (is_partition_root(cs)) { + int ret = update_flag(CS_PARTITION_ROOT, cs, 0); + + WARN_ON_ONCE(ret); + } + + if (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) && + is_sched_load_balance(cs)) update_flag(CS_SCHED_LOAD_BALANCE, cs, 0); cpuset_dec(); -- 1.8.3.1