linux-kernel - [PATCH v2] sched/rt: Account execution time for cgroup and thread group if rt entity is task

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Date:   Mon, 23 Oct 2023 16:09:54 +0800
From:   Yajun Deng <yajun.deng@...ux.dev>
To:     mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        bristot@...hat.com, vschneid@...hat.com
Cc:     linux-kernel@...r.kernel.org, Yajun Deng <yajun.deng@...ux.dev>
Subject: [PATCH v2] sched/rt: Account execution time for cgroup and thread group if rt entity is task

The rt entity can be a task group. Like the fair scheduler class, we don't
need to account execution time for cgroup and thread group if the rt
entity isn't a task.

Check the scheduler class of the task and make sure that the rt entity is a
task.

Signed-off-by: Yajun Deng <yajun.deng@...ux.dev>
---
v2: Add the missing '#endif'.
v1: https://lore.kernel.org/all/20231023065418.1548239-1-yajun.deng@linux.dev/
---
 kernel/sched/rt.c    |  4 ----
 kernel/sched/sched.h | 13 +++++++++++--
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 6aaf0a3d6081..ccded5670b61 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -165,8 +165,6 @@ static void destroy_rt_bandwidth(struct rt_bandwidth *rt_b)
 	hrtimer_cancel(&rt_b->rt_period_timer);
 }
 
-#define rt_entity_is_task(rt_se) (!(rt_se)->my_q)
-
 static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
 {
 #ifdef CONFIG_SCHED_DEBUG
@@ -283,8 +281,6 @@ int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
 
 #else /* CONFIG_RT_GROUP_SCHED */
 
-#define rt_entity_is_task(rt_se) (1)
-
 static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
 {
 	return container_of(rt_se, struct task_struct, rt);
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 65cad0e5729e..95d696e23a89 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -779,6 +779,12 @@ static inline long se_runnable(struct sched_entity *se)
 }
 #endif
 
+#ifdef CONFIG_RT_GROUP_SCHED
+#define rt_entity_is_task(rt_se) (!(rt_se)->my_q)
+#else
+#define rt_entity_is_task(rt_se) (1)
+#endif
+
 #ifdef CONFIG_SMP
 /*
  * XXX we want to get rid of these helpers and use the full load resolution.
@@ -3266,9 +3272,12 @@ static inline void update_current_exec_runtime(struct task_struct *curr,
 						u64 now, u64 delta_exec)
 {
 	curr->se.sum_exec_runtime += delta_exec;
-	account_group_exec_runtime(curr, delta_exec);
-
 	curr->se.exec_start = now;
+
+	if (curr->sched_class == &rt_sched_class && !rt_entity_is_task(&curr->rt))
+		return;
+
+	account_group_exec_runtime(curr, delta_exec);
 	cgroup_account_cputime(curr, delta_exec);
 }
 
-- 
2.25.1