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Date: Thu, 16 Mar 2023 16:18:06 +0800
From: Hao Jia <jiahao.os@...edance.com>
To: mingo@...hat.com, peterz@...radead.org, mingo@...nel.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,
mgorman@...hsingularity.net
Cc: linux-kernel@...r.kernel.org, Hao Jia <jiahao.os@...edance.com>,
Cruz Zhao <CruzZhao@...ux.alibaba.com>
Subject: [PATCH] sched/core: Avoid selecting the task that is throttled to run when core-sched enable
When {rt, cfs}_rq or dl task is throttled, since cookied tasks
are not dequeued from the core tree, So sched_core_find() and
sched_core_next() may return throttled task, which may
cause throttled task to run on the CPU.
So we add checks in sched_core_find() and sched_core_next()
to make sure that the return is a runnable task that is
not throttled.
Co-developed-by: Cruz Zhao <CruzZhao@...ux.alibaba.com>
Signed-off-by: Cruz Zhao <CruzZhao@...ux.alibaba.com>
Signed-off-by: Hao Jia <jiahao.os@...edance.com>
---
kernel/sched/core.c | 60 ++++++++++++++++++++++++++++-------------
kernel/sched/deadline.c | 10 +++++++
kernel/sched/fair.c | 16 +++++++++++
kernel/sched/rt.c | 19 +++++++++++++
kernel/sched/sched.h | 4 +++
5 files changed, 90 insertions(+), 19 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index af017e038b48..27cb06e19b12 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -261,36 +261,51 @@ void sched_core_dequeue(struct rq *rq, struct task_struct *p, int flags)
resched_curr(rq);
}
-/*
- * Find left-most (aka, highest priority) task matching @cookie.
- */
-static struct task_struct *sched_core_find(struct rq *rq, unsigned long cookie)
+static int sched_task_is_throttled(struct task_struct *p, int cpu)
{
- struct rb_node *node;
-
- node = rb_find_first((void *)cookie, &rq->core_tree, rb_sched_core_cmp);
- /*
- * The idle task always matches any cookie!
- */
- if (!node)
- return idle_sched_class.pick_task(rq);
+ if (p->sched_class->task_is_throttled)
+ return p->sched_class->task_is_throttled(p, cpu);
- return __node_2_sc(node);
+ return 0;
}
static struct task_struct *sched_core_next(struct task_struct *p, unsigned long cookie)
{
struct rb_node *node = &p->core_node;
+ int cpu = task_cpu(p);
+
+ do {
+ node = rb_next(node);
+ if (!node)
+ return NULL;
+
+ p = container_of(node, struct task_struct, core_node);
+ if (p->core_cookie != cookie)
+ return NULL;
+ } while (sched_task_is_throttled(p, cpu));
+
+ return p;
+}
- node = rb_next(node);
+/*
+ * Find left-most (aka, highest priority) and unthrottled task matching @cookie.
+ * If no suitable task is found, NULL will be returned.
+ */
+static struct task_struct *sched_core_find(struct rq *rq, unsigned long cookie)
+{
+ struct task_struct *p;
+ struct rb_node *node;
+
+ node = rb_find_first((void *)cookie, &rq->core_tree, rb_sched_core_cmp);
if (!node)
return NULL;
- p = container_of(node, struct task_struct, core_node);
- if (p->core_cookie != cookie)
- return NULL;
+ p = __node_2_sc(node);
- return p;
+ if (!sched_task_is_throttled(p, rq->cpu))
+ return p;
+
+ return sched_core_next(p, cookie);
}
/*
@@ -6236,7 +6251,7 @@ static bool try_steal_cookie(int this, int that)
goto unlock;
p = sched_core_find(src, cookie);
- if (p == src->idle)
+ if (!p)
goto unlock;
do {
@@ -6248,6 +6263,13 @@ static bool try_steal_cookie(int this, int that)
if (p->core_occupation > dst->idle->core_occupation)
goto next;
+ /*
+ * sched_core_find() and sched_core_next() will ensure that task @p
+ * is not throttled now, we also need to check whether the runqueue
+ * of the destination CPU is being throttled.
+ */
+ if (sched_task_is_throttled(p, this))
+ goto next;
deactivate_task(src, p, 0);
set_task_cpu(p, this);
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 71b24371a6f7..4cc7e1ca066d 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -2704,6 +2704,13 @@ static void prio_changed_dl(struct rq *rq, struct task_struct *p,
#endif
}
+#ifdef CONFIG_SCHED_CORE
+static int task_is_throttled_dl(struct task_struct *p, int cpu)
+{
+ return p->dl.dl_throttled;
+}
+#endif
+
DEFINE_SCHED_CLASS(dl) = {
.enqueue_task = enqueue_task_dl,
@@ -2736,6 +2743,9 @@ DEFINE_SCHED_CLASS(dl) = {
.switched_to = switched_to_dl,
.update_curr = update_curr_dl,
+#ifdef CONFIG_SCHED_CORE
+ .task_is_throttled = task_is_throttled_dl,
+#endif
};
/* Used for dl_bw check and update, used under sched_rt_handler()::mutex */
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 7a1b1f855b96..b572367249f0 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -11933,6 +11933,18 @@ bool cfs_prio_less(const struct task_struct *a, const struct task_struct *b,
return delta > 0;
}
+
+static int task_is_throttled_fair(struct task_struct *p, int cpu)
+{
+ struct cfs_rq *cfs_rq;
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+ cfs_rq = task_group(p)->cfs_rq[cpu];
+#else
+ cfs_rq = &cpu_rq(cpu)->cfs;
+#endif
+ return throttled_hierarchy(cfs_rq);
+}
#else
static inline void task_tick_core(struct rq *rq, struct task_struct *curr) {}
#endif
@@ -12559,6 +12571,10 @@ DEFINE_SCHED_CLASS(fair) = {
.task_change_group = task_change_group_fair,
#endif
+#ifdef CONFIG_SCHED_CORE
+ .task_is_throttled = task_is_throttled_fair,
+#endif
+
#ifdef CONFIG_UCLAMP_TASK
.uclamp_enabled = 1,
#endif
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 0a11f44adee5..9d67dfbf1000 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -2677,6 +2677,21 @@ static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
return 0;
}
+#ifdef CONFIG_SCHED_CORE
+static int task_is_throttled_rt(struct task_struct *p, int cpu)
+{
+ struct rt_rq *rt_rq;
+
+#ifdef CONFIG_RT_GROUP_SCHED
+ rt_rq = task_group(p)->rt_rq[cpu];
+#else
+ rt_rq = &cpu_rq(cpu)->rt;
+#endif
+
+ return rt_rq_throttled(rt_rq);
+}
+#endif
+
DEFINE_SCHED_CLASS(rt) = {
.enqueue_task = enqueue_task_rt,
@@ -2710,6 +2725,10 @@ DEFINE_SCHED_CLASS(rt) = {
.update_curr = update_curr_rt,
+#ifdef CONFIG_SCHED_CORE
+ .task_is_throttled = task_is_throttled_rt,
+#endif
+
#ifdef CONFIG_UCLAMP_TASK
.uclamp_enabled = 1,
#endif
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 3e8df6d31c1e..060616944d7a 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2224,6 +2224,10 @@ struct sched_class {
#ifdef CONFIG_FAIR_GROUP_SCHED
void (*task_change_group)(struct task_struct *p);
#endif
+
+#ifdef CONFIG_SCHED_CORE
+ int (*task_is_throttled)(struct task_struct *p, int cpu);
+#endif
};
static inline void put_prev_task(struct rq *rq, struct task_struct *prev)
--
2.37.0
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