[PATCH v12 3/9] cpuset: Simulate auto-off of sched.partition at cgroup removal
From: Waiman Long <longman@redhat.com>
Date: 2018-08-27 14:41:43
Also in:
cgroups, lkml
Subsystem:
control group (cgroup), control group - cpuset, the rest · Maintainers:
Tejun Heo, Johannes Weiner, Michal Koutný, Waiman Long, Linus Torvalds
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 <longman@redhat.com> --- 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 fdaa051..d9e821c 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c@@ -2253,7 +2253,12 @@ 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)
@@ -2262,7 +2267,18 @@ 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