7246544786
Sometimes ->nr_running may cross 2 but interrupt is not being sent to rq's cpu. In this case we don't reenable the timer. Looks like this may be the reason for rare unexpected effects, if nohz is enabled. Patch replaces all places of direct changing of nr_running and makes add_nr_running() caring about crossing border. Signed-off-by: Kirill Tkhai <tkhai@yandex.ru> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20140508225830.2469.97461.stgit@localhost Signed-off-by: Ingo Molnar <mingo@kernel.org>
132 lines
2.8 KiB
C
132 lines
2.8 KiB
C
#include "sched.h"
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/*
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* stop-task scheduling class.
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*
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* The stop task is the highest priority task in the system, it preempts
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* everything and will be preempted by nothing.
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*
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* See kernel/stop_machine.c
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*/
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#ifdef CONFIG_SMP
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static int
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select_task_rq_stop(struct task_struct *p, int cpu, int sd_flag, int flags)
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{
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return task_cpu(p); /* stop tasks as never migrate */
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}
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#endif /* CONFIG_SMP */
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static void
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check_preempt_curr_stop(struct rq *rq, struct task_struct *p, int flags)
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{
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/* we're never preempted */
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}
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static struct task_struct *
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pick_next_task_stop(struct rq *rq, struct task_struct *prev)
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{
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struct task_struct *stop = rq->stop;
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if (!stop || !stop->on_rq)
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return NULL;
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put_prev_task(rq, prev);
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stop->se.exec_start = rq_clock_task(rq);
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return stop;
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}
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static void
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enqueue_task_stop(struct rq *rq, struct task_struct *p, int flags)
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{
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add_nr_running(rq, 1);
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}
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static void
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dequeue_task_stop(struct rq *rq, struct task_struct *p, int flags)
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{
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sub_nr_running(rq, 1);
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}
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static void yield_task_stop(struct rq *rq)
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{
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BUG(); /* the stop task should never yield, its pointless. */
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}
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static void put_prev_task_stop(struct rq *rq, struct task_struct *prev)
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{
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struct task_struct *curr = rq->curr;
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u64 delta_exec;
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delta_exec = rq_clock_task(rq) - curr->se.exec_start;
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if (unlikely((s64)delta_exec < 0))
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delta_exec = 0;
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schedstat_set(curr->se.statistics.exec_max,
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max(curr->se.statistics.exec_max, delta_exec));
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curr->se.sum_exec_runtime += delta_exec;
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account_group_exec_runtime(curr, delta_exec);
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curr->se.exec_start = rq_clock_task(rq);
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cpuacct_charge(curr, delta_exec);
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}
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static void task_tick_stop(struct rq *rq, struct task_struct *curr, int queued)
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{
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}
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static void set_curr_task_stop(struct rq *rq)
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{
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struct task_struct *stop = rq->stop;
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stop->se.exec_start = rq_clock_task(rq);
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}
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static void switched_to_stop(struct rq *rq, struct task_struct *p)
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{
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BUG(); /* its impossible to change to this class */
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}
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static void
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prio_changed_stop(struct rq *rq, struct task_struct *p, int oldprio)
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{
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BUG(); /* how!?, what priority? */
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}
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static unsigned int
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get_rr_interval_stop(struct rq *rq, struct task_struct *task)
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{
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return 0;
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}
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/*
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* Simple, special scheduling class for the per-CPU stop tasks:
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*/
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const struct sched_class stop_sched_class = {
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.next = &dl_sched_class,
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.enqueue_task = enqueue_task_stop,
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.dequeue_task = dequeue_task_stop,
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.yield_task = yield_task_stop,
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.check_preempt_curr = check_preempt_curr_stop,
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.pick_next_task = pick_next_task_stop,
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.put_prev_task = put_prev_task_stop,
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#ifdef CONFIG_SMP
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.select_task_rq = select_task_rq_stop,
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#endif
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.set_curr_task = set_curr_task_stop,
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.task_tick = task_tick_stop,
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.get_rr_interval = get_rr_interval_stop,
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.prio_changed = prio_changed_stop,
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.switched_to = switched_to_stop,
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};
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