Messages in this thread Patch in this message | | | Date | Mon, 18 Feb 2019 17:56:29 +0100 | From | Peter Zijlstra <> | Subject | [RFC][PATCH 09/16] sched: Introduce sched_class::pick_task() |
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Because sched_class::pick_next_task() also implies sched_class::set_next_task() (and possibly put_prev_task() and newidle_balance) it is not state invariant. This makes it unsuitable for remote task selection.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- kernel/sched/deadline.c | 21 ++++++++++++++++----- kernel/sched/fair.c | 30 ++++++++++++++++++++++++++++++ kernel/sched/idle.c | 10 +++++++++- kernel/sched/rt.c | 21 ++++++++++++++++----- kernel/sched/sched.h | 2 ++ kernel/sched/stop_task.c | 21 ++++++++++++++++----- 6 files changed, 89 insertions(+), 16 deletions(-)
--- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1723,15 +1723,12 @@ static struct sched_dl_entity *pick_next return rb_entry(left, struct sched_dl_entity, rb_node); } -static struct task_struct * -pick_next_task_dl(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) +static struct task_struct *pick_task_dl(struct rq *rq) { struct sched_dl_entity *dl_se; struct task_struct *p; struct dl_rq *dl_rq; - WARN_ON_ONCE(prev || rf); - dl_rq = &rq->dl; if (unlikely(!dl_rq->dl_nr_running)) @@ -1742,7 +1739,19 @@ pick_next_task_dl(struct rq *rq, struct p = dl_task_of(dl_se); - set_next_task_dl(rq, p); + return p; +} + +static struct task_struct * +pick_next_task_dl(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) +{ + struct task_struct *p; + + WARN_ON_ONCE(prev || rf); + + p = pick_task_dl(rq); + if (p) + set_next_task_dl(rq, p); return p; } @@ -2389,6 +2398,8 @@ const struct sched_class dl_sched_class .set_next_task = set_next_task_dl, #ifdef CONFIG_SMP + .pick_task = pick_task_dl, + .select_task_rq = select_task_rq_dl, .migrate_task_rq = migrate_task_rq_dl, .set_cpus_allowed = set_cpus_allowed_dl, --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6937,6 +6937,34 @@ static void check_preempt_wakeup(struct } static struct task_struct * +pick_task_fair(struct rq *rq) +{ + struct cfs_rq *cfs_rq = &rq->cfs; + struct sched_entity *se; + + if (!cfs_rq->nr_running) + return NULL; + + do { + struct sched_entity *curr = cfs_rq->curr; + + se = pick_next_entity(cfs_rq, NULL); + + if (curr) { + if (se && curr->on_rq) + update_curr(cfs_rq); + + if (!se || entity_before(curr, se)) + se = curr; + } + + cfs_rq = group_cfs_rq(se); + } while (cfs_rq); + + return task_of(se); +} + +static struct task_struct * pick_next_task_fair(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) { struct cfs_rq *cfs_rq = &rq->cfs; @@ -10604,6 +10632,8 @@ const struct sched_class fair_sched_clas .set_next_task = set_next_task_fair, #ifdef CONFIG_SMP + .pick_task = pick_task_fair, + .select_task_rq = select_task_rq_fair, .migrate_task_rq = migrate_task_rq_fair, --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -373,6 +373,12 @@ static void check_preempt_curr_idle(stru resched_curr(rq); } +static struct task_struct * +pick_task_idle(struct rq *rq) +{ + return rq->idle; +} + static void put_prev_task_idle(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) { } @@ -386,11 +392,12 @@ static void set_next_task_idle(struct rq static struct task_struct * pick_next_task_idle(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) { - struct task_struct *next = rq->idle; + struct task_struct *next; if (prev) put_prev_task(rq, prev); + next = pick_task_idle(rq); set_next_task_idle(rq, next); return next; @@ -458,6 +465,7 @@ const struct sched_class idle_sched_clas .set_next_task = set_next_task_idle, #ifdef CONFIG_SMP + .pick_task = pick_task_idle, .select_task_rq = select_task_rq_idle, .set_cpus_allowed = set_cpus_allowed_common, #endif --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1548,20 +1548,29 @@ static struct task_struct *_pick_next_ta return rt_task_of(rt_se); } -static struct task_struct * -pick_next_task_rt(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) +static struct task_struct *pick_task_rt(struct rq *rq) { struct task_struct *p; struct rt_rq *rt_rq = &rq->rt; - WARN_ON_ONCE(prev || rf); - if (!rt_rq->rt_queued) return NULL; p = _pick_next_task_rt(rq); - set_next_task_rt(rq, p); + return p; +} + +static struct task_struct * +pick_next_task_rt(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) +{ + struct task_struct *p; + + WARN_ON_ONCE(prev || rf); + + p = pick_task_rt(rq); + if (p) + set_next_task_rt(rq, p); return p; } @@ -2364,6 +2373,8 @@ const struct sched_class rt_sched_class .set_next_task = set_next_task_rt, #ifdef CONFIG_SMP + .pick_task = pick_task_rt, + .select_task_rq = select_task_rq_rt, .set_cpus_allowed = set_cpus_allowed_common, --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1682,6 +1682,8 @@ struct sched_class { void (*set_next_task)(struct rq *rq, struct task_struct *p); #ifdef CONFIG_SMP + struct task_struct * (*pick_task)(struct rq *rq); + int (*select_task_rq)(struct task_struct *p, int task_cpu, int sd_flag, int flags); void (*migrate_task_rq)(struct task_struct *p, int new_cpu); --- a/kernel/sched/stop_task.c +++ b/kernel/sched/stop_task.c @@ -29,20 +29,30 @@ static void set_next_task_stop(struct rq } static struct task_struct * -pick_next_task_stop(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) +pick_task_stop(struct rq *rq) { struct task_struct *stop = rq->stop; - WARN_ON_ONCE(prev || rf); - if (!stop || !task_on_rq_queued(stop)) return NULL; - set_next_task_stop(rq, stop); - return stop; } +static struct task_struct * +pick_next_task_stop(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) +{ + struct task_struct *p; + + WARN_ON_ONCE(prev || rf); + + p = pick_task_stop(rq); + if (p) + set_next_task_stop(rq, p); + + return p; +} + static void enqueue_task_stop(struct rq *rq, struct task_struct *p, int flags) { @@ -129,6 +139,7 @@ const struct sched_class stop_sched_clas .set_next_task = set_next_task_stop, #ifdef CONFIG_SMP + .pick_task = pick_task_stop, .select_task_rq = select_task_rq_stop, .set_cpus_allowed = set_cpus_allowed_common, #endif
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