From 530bfad1d53d103f98cec66a3e491a36d397884d Mon Sep 17 00:00:00 2001 From: Hao Jia Date: Thu, 16 Mar 2023 16:18:06 +0800 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 Signed-off-by: Cruz Zhao Signed-off-by: Hao Jia Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20230316081806.69544-1-jiahao.os@bytedance.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 488655f..9140a33 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 = __node_2_sc(node); + if (p->core_cookie != cookie) + return NULL; + + } while (sched_task_is_throttled(p, cpu)); + + return p; +} + +/* + * 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_next(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); + if (!sched_task_is_throttled(p, rq->cpu)) + return p; - 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 71b2437..4cc7e1c 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 7a1b1f8..b572367 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 0a11f44..9d67dfb 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 3e8df6d..0606169 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) -- 2.7.4