From: luca abeni <luca.abeni@santannapisa.it>
Allow creation of cgroup hierachies with depth greater than two.
Add check to prevent attaching tasks to a child cgroup of an active cgroup (i.e.
with a running FIFO/RR task).
Add check to prevent attaching tasks to cgroups which have children with
non-zero runtime.
Update rt-cgroups allocated bandwidth accounting for nested cgroup hierachies.
Co-developed-by: Yuri Andriaccio <yurand2000@gmail.com>
Signed-off-by: Yuri Andriaccio <yurand2000@gmail.com>
Signed-off-by: luca abeni <luca.abeni@santannapisa.it>
---
kernel/sched/core.c | 6 -----
kernel/sched/deadline.c | 51 +++++++++++++++++++++++++++++++++++++----
kernel/sched/rt.c | 16 ++++++++++---
kernel/sched/sched.h | 3 ++-
4 files changed, 62 insertions(+), 14 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 6f516cdc7bb..d1d7215c4a2 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -9281,12 +9281,6 @@ cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
return &root_task_group.css;
}
- /* Do not allow cpu_cgroup hierachies with depth greater than 2. */
-#ifdef CONFIG_RT_GROUP_SCHED
- if (parent != &root_task_group)
- return ERR_PTR(-EINVAL);
-#endif
-
tg = sched_create_group(parent);
if (IS_ERR(tg))
return ERR_PTR(-ENOMEM);
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 5d93b3ca030..abe11985c41 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -388,11 +388,42 @@ int dl_check_tg(unsigned long total)
return 1;
}
-void dl_init_tg(struct sched_dl_entity *dl_se, u64 rt_runtime, u64 rt_period)
+bool is_active_sched_group(struct task_group *tg)
{
+ struct task_group *child;
+ bool is_active = 1;
+
+ // if there are no children, this is a leaf group, thus it is active
+ list_for_each_entry_rcu(child, &tg->children, siblings) {
+ if (child->dl_bandwidth.dl_runtime > 0) {
+ is_active = 0;
+ }
+ }
+ return is_active;
+}
+
+static inline bool sched_group_has_active_siblings(struct task_group *tg)
+{
+ struct task_group *child;
+ bool has_active_siblings = 0;
+
+ // if there are no children, this is a leaf group, thus it is active
+ list_for_each_entry_rcu(child, &tg->parent->children, siblings) {
+ if (child != tg && child->dl_bandwidth.dl_runtime > 0) {
+ has_active_siblings = 1;
+ }
+ }
+ return has_active_siblings;
+}
+
+void dl_init_tg(struct task_group *tg, int cpu, u64 rt_runtime, u64 rt_period)
+{
+ struct sched_dl_entity *dl_se = tg->dl_se[cpu];
struct rq *rq = container_of(dl_se->dl_rq, struct rq, dl);
- int is_active;
- u64 new_bw;
+ int is_active, is_active_group;
+ u64 old_runtime, new_bw;
+
+ is_active_group = is_active_sched_group(tg);
raw_spin_rq_lock_irq(rq);
is_active = dl_se->my_q->rt.rt_nr_running > 0;
@@ -400,8 +431,10 @@ void dl_init_tg(struct sched_dl_entity *dl_se, u64 rt_runtime, u64 rt_period)
update_rq_clock(rq);
dl_server_stop(dl_se);
+ old_runtime = dl_se->dl_runtime;
new_bw = to_ratio(dl_se->dl_period, dl_se->dl_runtime);
- dl_rq_change_utilization(rq, dl_se, new_bw);
+ if (is_active_group)
+ dl_rq_change_utilization(rq, dl_se, new_bw);
dl_se->dl_runtime = rt_runtime;
dl_se->dl_deadline = rt_period;
@@ -413,6 +446,16 @@ void dl_init_tg(struct sched_dl_entity *dl_se, u64 rt_runtime, u64 rt_period)
dl_se->dl_bw = new_bw;
dl_se->dl_density = new_bw;
+ // add/remove the parent's bw
+ if (tg->parent && tg->parent != &root_task_group)
+ {
+ if (rt_runtime == 0 && old_runtime != 0 && !sched_group_has_active_siblings(tg)) {
+ __add_rq_bw(tg->parent->dl_se[cpu]->dl_bw, dl_se->dl_rq);
+ } else if (rt_runtime != 0 && old_runtime == 0 && !sched_group_has_active_siblings(tg)) {
+ __sub_rq_bw(tg->parent->dl_se[cpu]->dl_bw, dl_se->dl_rq);
+ }
+ }
+
if (is_active)
dl_server_start(dl_se);
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 1cdc699bbb7..17ad91261cb 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -114,7 +114,8 @@ void free_rt_sched_group(struct task_group *tg)
* Fix this issue by changing the group runtime
* to 0 immediately before freeing it.
*/
- dl_init_tg(tg->dl_se[i], 0, tg->dl_se[i]->dl_period);
+ if (tg->dl_se[i]->dl_runtime)
+ dl_init_tg(tg, i, 0, tg->dl_se[i]->dl_period);
raw_spin_rq_lock_irqsave(cpu_rq(i), flags);
BUG_ON(tg->rt_rq[i]->rt_nr_running);
@@ -2122,6 +2123,14 @@ static int tg_set_rt_bandwidth(struct task_group *tg,
static DEFINE_MUTEX(rt_constraints_mutex);
int i, err = 0;
+ /*
+ * Do not allow to set a RT runtime > 0 if the parent has RT tasks
+ * (and is not the root group)
+ */
+ if (rt_runtime && (tg != &root_task_group) && (tg->parent != &root_task_group) && tg_has_rt_tasks(tg->parent)) {
+ return -EINVAL;
+ }
+
/* No period doesn't make any sense. */
if (rt_period == 0)
return -EINVAL;
@@ -2145,7 +2154,7 @@ static int tg_set_rt_bandwidth(struct task_group *tg,
return 0;
for_each_possible_cpu(i) {
- dl_init_tg(tg->dl_se[i], rt_runtime, rt_period);
+ dl_init_tg(tg, i, rt_runtime, rt_period);
}
return 0;
@@ -2216,7 +2225,8 @@ int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk)
if (rt_group_sched_enabled() && tg->dl_bandwidth.dl_runtime == 0)
return 0;
- return 1;
+ /* tasks can be attached only if the taskgroup has no active children. */
+ return (int)is_active_sched_group(tg);
}
#else /* !CONFIG_RT_GROUP_SCHED: */
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index fddb171145e..55631d93e02 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -386,7 +386,8 @@ extern void dl_server_init(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq,
dl_server_pick_f pick_task);
extern void sched_init_dl_servers(void);
extern int dl_check_tg(unsigned long total);
-extern void dl_init_tg(struct sched_dl_entity *dl_se, u64 rt_runtime, u64 rt_period);
+extern void dl_init_tg(struct task_group *tg, int cpu, u64 rt_runtime, u64 rt_period);
+extern bool is_active_sched_group(struct task_group *tg);
extern void dl_server_update_idle_time(struct rq *rq,
struct task_struct *p);
--
2.51.0