On Wed, 2014-06-11 at 23:33 +0400, Kirill Tkhai wrote: > В Ср, 11/06/2014 в 17:43 +0400, Kirill Tkhai пишет: > > > > 11.06.2014, 17:15, "Srikar Dronamraju" <[email protected]>: > > >>> * Kirill Tkhai <[email protected]> [2014-06-11 13:52:10]: > > >>>> Currently migrate_tasks() skips throttled tasks, > > >>>> because they are not pickable by pick_next_task(). > > >>> Before migrate_tasks() is called, we do call set_rq_offline(), in > > >>> migration_call(). > > >>> > > >>> Shouldnt this take care of unthrottling the tasks and making sure that > > >>> they can be picked by pick_next_task(). > > >> If we do this separate for every class, we'll have to do this 3 times. > > >> Furthermore, deadline class does not have a list of throttled tasks. > > >> So we'll have to the same as I did: to lock tasklist_lock and to iterate > > >> throw all of the tasks in the system just to found deadline tasks. > > > > > > I think you misread my comment. > > > > > > Currently migrate_task() gets called from migration_call() and in the > > > migration_call() before migrate_tasks(), set_rq_offline() should put > > > tasks back using unthrottle_cfs_rq(). > > > > > > So my question is: Why are these tasks not getting unthrottled > > > through we are calling set_rq_offline? To me set_rq_offline is > > > calling the actual sched class routines to do the needful. > > > > > > I can understand about deadline tasks, because we don't have a deadline > > > But thats the only tasks that we need to fix. > > > > Hm, I tested that on fair class tasks. They used to disappear from > > /proc/sched_debug and used to hang. I'll check all once again. > > > > I'm agree with you, if set_rq_offline() already presents, we should use it. > > > > /me went to clarify why it does not work in my test. > > Ok, it looks like the problem is that unthrottled cfs_rq may become throttled > again ;)
Dejavu. You could try either of the below. On Thu, Apr 03, 2014 at 10:02:18AM +0200, Mike Galbraith wrote: > Prevent large wakeup latencies from being accounted to the wrong task. > > Cc: <[email protected]> > Signed-off-by: Mike Galbraith <[email protected]> > --- > kernel/sched/core.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -118,7 +118,12 @@ void update_rq_clock(struct rq *rq) > { > s64 delta; > > - if (rq->skip_clock_update > 0) > + /* > + * Set during wakeup to indicate we are on the way to schedule(). > + * Decrement to ensure that a very large latency is not accounted > + * to the wrong task. > + */ > + if (rq->skip_clock_update-- > 0) > return; > > delta = sched_clock_cpu(cpu_of(rq)) - rq->clock; OK; so as previously mentioned (Oct '13); I've entirely had it with skip_clock_update bugs, so I got angry and did the below. Its not something I can merge, not least because it uses trace_printk(), but it should be usable to 1) demonstate the above actually helps and 2) make damn sure we got it right this time :-) I've not really stared at the output much yet; but when you select function_graph tracer; we get lovely things like: 8) | wake_up_process() { 8) | try_to_wake_up() { 8) 0.076 us | _raw_spin_lock_irqsave(); 8) 0.092 us | task_waking_fair(); 8) 0.106 us | select_task_rq_fair(); 8) 0.161 us | _raw_spin_lock(); 8) | ttwu_do_activate.constprop.103() { 8) | activate_task() { 8) | enqueue_task() { 8) | update_rq_clock() { 8) | /* clock update: 420411 */ 8) 0.084 us | sched_avg_update(); 8) 1.277 us | } 8) | enqueue_task_fair() { 8) | enqueue_entity() { 8) 0.083 us | update_curr(); 8) 0.071 us | __compute_runnable_contrib(); 8) 0.074 us | __update_entity_load_avg_contrib(); 8) 0.121 us | update_cfs_rq_blocked_load(); 8) 0.236 us | account_entity_enqueue(); 8) 0.076 us | update_cfs_shares(); 8) 0.075 us | place_entity(); 8) 0.123 us | __enqueue_entity(); 8) 5.260 us | } 8) 0.069 us | __compute_runnable_contrib(); 8) 0.073 us | hrtick_update(); 8) 7.146 us | } 8) 9.583 us | } 8) + 10.169 us | } 8) | wq_worker_waking_up() { 8) 0.071 us | kthread_data(); 8) 0.682 us | } 8) | ttwu_do_wakeup() { 8) | check_preempt_curr() { 8) 0.077 us | resched_task(); 8) | /* skip_clock_update on cpu: 8 */ 8) 1.188 us | } 8) 1.914 us | } 8) + 14.533 us | } 8) 0.071 us | _raw_spin_unlock(); 8) 0.082 us | _raw_spin_unlock_irqrestore(); 8) + 18.874 us | } 8) + 19.509 us | } ... 8) | wake_up_process() { 8) | try_to_wake_up() { 8) 0.101 us | _raw_spin_lock_irqsave(); 8) 0.089 us | task_waking_fair(); 8) 0.071 us | select_task_rq_fair(); 8) 0.070 us | _raw_spin_lock(); 8) | ttwu_do_activate.constprop.103() { 8) | activate_task() { 8) | enqueue_task() { 8) | update_rq_clock() { 8) | /* Invalid clock skip on cpu: 8 */ 8) | /* clock update: 420413 */ 8) 0.942 us | } 8) | enqueue_task_fair() { 8) | enqueue_entity() { 8) 0.081 us | update_curr(); 8) 0.074 us | __compute_runnable_contrib(); 8) 0.069 us | __update_entity_load_avg_contrib(); 8) 0.091 us | update_cfs_rq_blocked_load(); 8) 0.108 us | account_entity_enqueue(); 8) 0.081 us | update_cfs_shares(); 8) 0.069 us | place_entity(); 8) 0.107 us | __enqueue_entity(); 8) 5.120 us | } 8) 0.068 us | hrtick_update(); 8) 6.410 us | } 8) 8.484 us | } 8) 9.045 us | } 8) | wq_worker_waking_up() { 8) 0.074 us | kthread_data(); 8) 0.669 us | } 8) | ttwu_do_wakeup() { 8) | check_preempt_curr() { 8) 0.091 us | resched_task(); 8) | /* skip_clock_update on cpu: 8 */ 8) 1.080 us | } 8) 1.709 us | } 8) + 13.007 us | } 8) 0.071 us | _raw_spin_unlock(); 8) 0.090 us | _raw_spin_unlock_irqrestore(); 8) + 17.105 us | } 8) + 17.702 us | } ... 8) | schedule_preempt_disabled() { 8) | schedule() { 8) | __schedule() { 8) 0.105 us | rcu_note_context_switch(); 8) 0.078 us | _raw_spin_lock(); 8) | update_rq_clock() { 8) | /* Invalid clock skip on cpu: 8 */ 8) | /* clock update: 420415 */ 8) 0.073 us | sched_avg_update(); 8) 1.630 us | } 8) 0.080 us | pick_next_task_stop(); 8) 0.112 us | pick_next_task_dl(); 8) 0.088 us | pick_next_task_rt(); 8) | pick_next_task_fair() { 8) | put_prev_task_idle() { 8) 0.118 us | idle_exit_fair(); 8) 0.709 us | } 8) | pick_next_entity() { 8) 0.071 us | clear_buddies(); 8) 0.721 us | } 8) | set_next_entity() { 8) 0.139 us | __dequeue_entity(); 8) 0.732 us | } 8) 3.804 us | } ------------------------------------------ 8) <idle>-0 => <...>-220 ------------------------------------------ 8) | finish_task_switch() { 8) 0.076 us | _raw_spin_unlock(); 8) 0.716 us | } 8) ! 1876.643 us | } 8) ! 1877.297 us | } /* schedule */ Also; did I say how much I hate that function_graph doesn't default to latency-format ? --- kernel/sched/core.c | 130 +++++++++++++++++++++++++++++------------------ kernel/sched/deadline.c | 6 +- kernel/sched/debug.c | 7 +- kernel/sched/fair.c | 50 ++++++++++-------- kernel/sched/idle_task.c | 4 - kernel/sched/proc.c | 4 - kernel/sched/rt.c | 4 - kernel/sched/sched.h | 105 ++++++++++++++++++++++--------------- lib/Kconfig.debug | 7 ++ 9 files changed, 195 insertions(+), 122 deletions(-) --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -135,11 +135,31 @@ void update_rq_clock(struct rq *rq) { s64 delta; +#ifdef CONFIG_SCHED_DEBUG_CLOCK + if (rq->skip_clock_update > 0 && rq->clock_stamp != rq->clock_seq) { + rq->skip_clock_update = 0; + trace_printk("Invalid clock skip on cpu: %d\n", rq->cpu); + goto do_update; + } +#endif + if (rq->skip_clock_update > 0) return; - delta = sched_clock_cpu(cpu_of(rq)) - rq->clock; - rq->clock += delta; +#ifdef CONFIG_SCHED_DEBUG_CLOCK + if (!(rq->clock_stamp & 1)) + trace_printk("clock update outside of rq->lock\n"); + + if (rq->clock_stamp == rq->clock_seq) + trace_printk("superfluous clock update\n"); + +do_update: + trace_printk("clock update: %u\n", rq->clock_seq); + rq->clock_stamp = rq->clock_seq; +#endif + + delta = sched_clock_cpu(cpu_of(rq)) - rq->__clock; + rq->__clock += delta; update_rq_clock_task(rq, delta); } @@ -325,10 +345,10 @@ static inline struct rq *__task_rq_lock( for (;;) { rq = task_rq(p); - raw_spin_lock(&rq->lock); + rq_lock(rq); if (likely(rq == task_rq(p))) return rq; - raw_spin_unlock(&rq->lock); + rq_unlock(rq); } } @@ -344,10 +364,10 @@ static struct rq *task_rq_lock(struct ta for (;;) { raw_spin_lock_irqsave(&p->pi_lock, *flags); rq = task_rq(p); - raw_spin_lock(&rq->lock); + rq_lock(rq); if (likely(rq == task_rq(p))) return rq; - raw_spin_unlock(&rq->lock); + rq_unlock(rq); raw_spin_unlock_irqrestore(&p->pi_lock, *flags); } } @@ -355,7 +375,7 @@ static struct rq *task_rq_lock(struct ta static void __task_rq_unlock(struct rq *rq) __releases(rq->lock) { - raw_spin_unlock(&rq->lock); + rq_unlock(rq); } static inline void @@ -363,7 +383,7 @@ task_rq_unlock(struct rq *rq, struct tas __releases(rq->lock) __releases(p->pi_lock) { - raw_spin_unlock(&rq->lock); + rq_unlock(rq); raw_spin_unlock_irqrestore(&p->pi_lock, *flags); } @@ -377,7 +397,7 @@ static struct rq *this_rq_lock(void) local_irq_disable(); rq = this_rq(); - raw_spin_lock(&rq->lock); + rq_lock(rq); return rq; } @@ -403,10 +423,10 @@ static enum hrtimer_restart hrtick(struc WARN_ON_ONCE(cpu_of(rq) != smp_processor_id()); - raw_spin_lock(&rq->lock); + rq_lock(rq); update_rq_clock(rq); rq->curr->sched_class->task_tick(rq, rq->curr, 1); - raw_spin_unlock(&rq->lock); + rq_unlock(rq); return HRTIMER_NORESTART; } @@ -428,10 +448,10 @@ static void __hrtick_start(void *arg) { struct rq *rq = arg; - raw_spin_lock(&rq->lock); + rq_lock(rq); __hrtick_restart(rq); rq->hrtick_csd_pending = 0; - raw_spin_unlock(&rq->lock); + rq_unlock(rq); } /* @@ -565,7 +585,7 @@ void resched_task(struct task_struct *p) { int cpu; - lockdep_assert_held(&task_rq(p)->lock); + lockdep_assert_held(&task_rq(p)->__lock); if (test_tsk_need_resched(p)) return; @@ -587,10 +607,10 @@ void resched_cpu(int cpu) struct rq *rq = cpu_rq(cpu); unsigned long flags; - if (!raw_spin_trylock_irqsave(&rq->lock, flags)) + if (!raw_spin_trylock_irqsave(&rq->__lock, flags)) return; resched_task(cpu_curr(cpu)); - raw_spin_unlock_irqrestore(&rq->lock, flags); + raw_spin_unlock_irqrestore(&rq->__lock, flags); } #ifdef CONFIG_SMP @@ -893,7 +913,7 @@ static void update_rq_clock_task(struct } #endif - rq->clock_task += delta; + rq->__clock_task += delta; #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING) if ((irq_delta + steal) && sched_feat(NONTASK_POWER)) @@ -1023,8 +1043,10 @@ void check_preempt_curr(struct rq *rq, s * A queue event has occurred, and we're going to schedule. In * this case, we can save a useless back to back clock update. */ - if (rq->curr->on_rq && test_tsk_need_resched(rq->curr)) + if (rq->curr->on_rq && test_tsk_need_resched(rq->curr)) { + trace_printk("skip_clock_update on cpu: %d\n", rq->cpu); rq->skip_clock_update = 1; + } } #ifdef CONFIG_SMP @@ -1535,7 +1557,7 @@ static void sched_ttwu_pending(void) struct llist_node *llist = llist_del_all(&rq->wake_list); struct task_struct *p; - raw_spin_lock(&rq->lock); + rq_lock(rq); while (llist) { p = llist_entry(llist, struct task_struct, wake_entry); @@ -1543,7 +1565,7 @@ static void sched_ttwu_pending(void) ttwu_do_activate(rq, p, 0); } - raw_spin_unlock(&rq->lock); + rq_unlock(rq); } void scheduler_ipi(void) @@ -1611,9 +1633,9 @@ static void ttwu_queue(struct task_struc } #endif - raw_spin_lock(&rq->lock); + rq_lock(rq); ttwu_do_activate(rq, p, 0); - raw_spin_unlock(&rq->lock); + rq_unlock(rq); } /** @@ -1704,12 +1726,12 @@ static void try_to_wake_up_local(struct WARN_ON_ONCE(p == current)) return; - lockdep_assert_held(&rq->lock); + lockdep_assert_held(&rq->__lock); if (!raw_spin_trylock(&p->pi_lock)) { - raw_spin_unlock(&rq->lock); + raw_spin_unlock(&rq->__lock); raw_spin_lock(&p->pi_lock); - raw_spin_lock(&rq->lock); + raw_spin_lock(&rq->__lock); } if (!(p->state & TASK_NORMAL)) @@ -2226,10 +2248,12 @@ static inline void post_schedule(struct if (rq->post_schedule) { unsigned long flags; - raw_spin_lock_irqsave(&rq->lock, flags); + local_irq_save(flags); + rq_lock(rq); if (rq->curr->sched_class->post_schedule) rq->curr->sched_class->post_schedule(rq); - raw_spin_unlock_irqrestore(&rq->lock, flags); + rq_unlock(rq); + local_irq_restore(flags); rq->post_schedule = 0; } @@ -2479,11 +2503,11 @@ void scheduler_tick(void) sched_clock_tick(); - raw_spin_lock(&rq->lock); + rq_lock(rq); update_rq_clock(rq); curr->sched_class->task_tick(rq, curr, 0); update_cpu_load_active(rq); - raw_spin_unlock(&rq->lock); + rq_unlock(rq); perf_event_task_tick(); @@ -2732,7 +2756,8 @@ static void __sched __schedule(void) * done by the caller to avoid the race with signal_wake_up(). */ smp_mb__before_spinlock(); - raw_spin_lock_irq(&rq->lock); + local_irq_disable(); + rq_lock(rq); switch_count = &prev->nivcsw; if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) { @@ -2780,8 +2805,10 @@ static void __sched __schedule(void) */ cpu = smp_processor_id(); rq = cpu_rq(cpu); - } else - raw_spin_unlock_irq(&rq->lock); + } else { + rq_unlock(rq); + local_irq_enable(); + } post_schedule(rq); @@ -4106,9 +4133,8 @@ SYSCALL_DEFINE0(sched_yield) * Since we are going to call schedule() anyway, there's * no need to preempt or enable interrupts: */ - __release(rq->lock); - spin_release(&rq->lock.dep_map, 1, _THIS_IP_); - do_raw_spin_unlock(&rq->lock); + preempt_disable(); + rq_unlock(rq); sched_preempt_enable_no_resched(); schedule(); @@ -4510,7 +4536,8 @@ void init_idle(struct task_struct *idle, struct rq *rq = cpu_rq(cpu); unsigned long flags; - raw_spin_lock_irqsave(&rq->lock, flags); + local_irq_save(flags); + rq_lock(rq); __sched_fork(0, idle); idle->state = TASK_RUNNING; @@ -4536,7 +4563,8 @@ void init_idle(struct task_struct *idle, #if defined(CONFIG_SMP) idle->on_cpu = 1; #endif - raw_spin_unlock_irqrestore(&rq->lock, flags); + rq_unlock(rq); + local_irq_restore(flags); /* Set the preempt count _outside_ the spinlocks! */ init_idle_preempt_count(idle, cpu); @@ -4835,11 +4863,11 @@ static void migrate_tasks(unsigned int d /* Find suitable destination for @next, with force if needed. */ dest_cpu = select_fallback_rq(dead_cpu, next); - raw_spin_unlock(&rq->lock); + rq_unlock(rq); __migrate_task(next, dead_cpu, dest_cpu); - raw_spin_lock(&rq->lock); + rq_lock(rq); } rq->stop = stop; @@ -5100,27 +5128,31 @@ migration_call(struct notifier_block *nf case CPU_ONLINE: /* Update our root-domain */ - raw_spin_lock_irqsave(&rq->lock, flags); + local_irq_save(flags); + rq_lock(rq); if (rq->rd) { BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); set_rq_online(rq); } - raw_spin_unlock_irqrestore(&rq->lock, flags); + rq_unlock(rq); + local_irq_restore(flags); break; #ifdef CONFIG_HOTPLUG_CPU case CPU_DYING: sched_ttwu_pending(); /* Update our root-domain */ - raw_spin_lock_irqsave(&rq->lock, flags); + local_irq_save(flags); + rq_lock(rq); if (rq->rd) { BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); set_rq_offline(rq); } migrate_tasks(cpu); BUG_ON(rq->nr_running != 1); /* the migration thread */ - raw_spin_unlock_irqrestore(&rq->lock, flags); + rq_unlock(rq); + local_irq_restore(flags); break; case CPU_DEAD: @@ -5427,7 +5459,8 @@ static void rq_attach_root(struct rq *rq struct root_domain *old_rd = NULL; unsigned long flags; - raw_spin_lock_irqsave(&rq->lock, flags); + local_irq_save(flags); + rq_lock(rq); if (rq->rd) { old_rd = rq->rd; @@ -5453,7 +5486,8 @@ static void rq_attach_root(struct rq *rq if (cpumask_test_cpu(rq->cpu, cpu_active_mask)) set_rq_online(rq); - raw_spin_unlock_irqrestore(&rq->lock, flags); + rq_unlock(rq); + local_irq_restore(flags); if (old_rd) call_rcu_sched(&old_rd->rcu, free_rootdomain); @@ -6931,7 +6965,7 @@ void __init sched_init(void) struct rq *rq; rq = cpu_rq(i); - raw_spin_lock_init(&rq->lock); + raw_spin_lock_init(&rq->__lock); rq->nr_running = 0; rq->calc_load_active = 0; rq->calc_load_update = jiffies + LOAD_FREQ; @@ -7842,13 +7876,13 @@ static int tg_set_cfs_bandwidth(struct t struct cfs_rq *cfs_rq = tg->cfs_rq[i]; struct rq *rq = cfs_rq->rq; - raw_spin_lock_irq(&rq->lock); + raw_spin_lock_irq(&rq->__lock); cfs_rq->runtime_enabled = runtime_enabled; cfs_rq->runtime_remaining = 0; if (cfs_rq->throttled) unthrottle_cfs_rq(cfs_rq); - raw_spin_unlock_irq(&rq->lock); + raw_spin_unlock_irq(&rq->__lock); } if (runtime_was_enabled && !runtime_enabled) cfs_bandwidth_usage_dec(); --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -511,11 +511,11 @@ static enum hrtimer_restart dl_task_time struct rq *rq; again: rq = task_rq(p); - raw_spin_lock(&rq->lock); + rq_lock(rq); if (rq != task_rq(p)) { /* Task was moved, retrying. */ - raw_spin_unlock(&rq->lock); + rq_unlock(rq); goto again; } @@ -548,7 +548,7 @@ static enum hrtimer_restart dl_task_time #endif } unlock: - raw_spin_unlock(&rq->lock); + rq_unlock(rq); return HRTIMER_NORESTART; } --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -187,7 +187,7 @@ void print_cfs_rq(struct seq_file *m, in SEQ_printf(m, " .%-30s: %Ld.%06ld\n", "exec_clock", SPLIT_NS(cfs_rq->exec_clock)); - raw_spin_lock_irqsave(&rq->lock, flags); + raw_spin_lock_irqsave(&rq->__lock, flags); if (cfs_rq->rb_leftmost) MIN_vruntime = (__pick_first_entity(cfs_rq))->vruntime; last = __pick_last_entity(cfs_rq); @@ -195,7 +195,7 @@ void print_cfs_rq(struct seq_file *m, in max_vruntime = last->vruntime; min_vruntime = cfs_rq->min_vruntime; rq0_min_vruntime = cpu_rq(0)->cfs.min_vruntime; - raw_spin_unlock_irqrestore(&rq->lock, flags); + raw_spin_unlock_irqrestore(&rq->__lock, flags); SEQ_printf(m, " .%-30s: %Ld.%06ld\n", "MIN_vruntime", SPLIT_NS(MIN_vruntime)); SEQ_printf(m, " .%-30s: %Ld.%06ld\n", "min_vruntime", @@ -301,7 +301,8 @@ do { \ P(nr_uninterruptible); PN(next_balance); SEQ_printf(m, " .%-30s: %ld\n", "curr->pid", (long)(task_pid_nr(rq->curr))); - PN(clock); + PN(__clock); + PN(__clock_task); P(cpu_load[0]); P(cpu_load[1]); P(cpu_load[2]); --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -3421,7 +3421,7 @@ static u64 distribute_cfs_runtime(struct throttled_list) { struct rq *rq = rq_of(cfs_rq); - raw_spin_lock(&rq->lock); + raw_spin_lock(&rq->__lock); if (!cfs_rq_throttled(cfs_rq)) goto next; @@ -3438,7 +3438,7 @@ static u64 distribute_cfs_runtime(struct unthrottle_cfs_rq(cfs_rq); next: - raw_spin_unlock(&rq->lock); + raw_spin_unlock(&rq->__lock); if (!remaining) break; @@ -4901,7 +4901,8 @@ static void yield_task_fair(struct rq *r * so we don't do microscopic update in schedule() * and double the fastpath cost. */ - rq->skip_clock_update = 1; + trace_printk("skip_clock_update on cpu: %d\n", rq->cpu); + rq->skip_clock_update = 1; } set_skip_buddy(se); @@ -5446,7 +5447,8 @@ static void update_blocked_averages(int struct cfs_rq *cfs_rq; unsigned long flags; - raw_spin_lock_irqsave(&rq->lock, flags); + local_irq_save(flags); + rq_lock(rq); update_rq_clock(rq); /* * Iterates the task_group tree in a bottom up fashion, see @@ -5461,7 +5463,8 @@ static void update_blocked_averages(int __update_blocked_averages_cpu(cfs_rq->tg, rq->cpu); } - raw_spin_unlock_irqrestore(&rq->lock, flags); + rq_unlock(rq); + local_irq_restore(flags); } /* @@ -6641,7 +6644,7 @@ static int load_balance(int this_cpu, st sd->nr_balance_failed++; if (need_active_balance(&env)) { - raw_spin_lock_irqsave(&busiest->lock, flags); + raw_spin_lock_irqsave(&busiest->__lock, flags); /* don't kick the active_load_balance_cpu_stop, * if the curr task on busiest cpu can't be @@ -6649,7 +6652,7 @@ static int load_balance(int this_cpu, st */ if (!cpumask_test_cpu(this_cpu, tsk_cpus_allowed(busiest->curr))) { - raw_spin_unlock_irqrestore(&busiest->lock, + raw_spin_unlock_irqrestore(&busiest->__lock, flags); env.flags |= LBF_ALL_PINNED; goto out_one_pinned; @@ -6665,7 +6668,7 @@ static int load_balance(int this_cpu, st busiest->push_cpu = this_cpu; active_balance = 1; } - raw_spin_unlock_irqrestore(&busiest->lock, flags); + raw_spin_unlock_irqrestore(&busiest->__lock, flags); if (active_balance) { stop_one_cpu_nowait(cpu_of(busiest), @@ -6775,7 +6778,7 @@ static int idle_balance(struct rq *this_ /* * Drop the rq->lock, but keep IRQ/preempt disabled. */ - raw_spin_unlock(&this_rq->lock); + raw_spin_unlock(&this_rq->__lock); update_blocked_averages(this_cpu); rcu_read_lock(); @@ -6816,7 +6819,7 @@ static int idle_balance(struct rq *this_ } rcu_read_unlock(); - raw_spin_lock(&this_rq->lock); + raw_spin_lock(&this_rq->__lock); if (curr_cost > this_rq->max_idle_balance_cost) this_rq->max_idle_balance_cost = curr_cost; @@ -6860,7 +6863,7 @@ static int active_load_balance_cpu_stop( struct rq *target_rq = cpu_rq(target_cpu); struct sched_domain *sd; - raw_spin_lock_irq(&busiest_rq->lock); + raw_spin_lock_irq(&busiest_rq->__lock); /* make sure the requested cpu hasn't gone down in the meantime */ if (unlikely(busiest_cpu != smp_processor_id() || @@ -6910,7 +6913,7 @@ static int active_load_balance_cpu_stop( double_unlock_balance(busiest_rq, target_rq); out_unlock: busiest_rq->active_balance = 0; - raw_spin_unlock_irq(&busiest_rq->lock); + raw_spin_unlock_irq(&busiest_rq->__lock); return 0; } @@ -7192,10 +7195,12 @@ static void nohz_idle_balance(struct rq rq = cpu_rq(balance_cpu); - raw_spin_lock_irq(&rq->lock); + local_irq_disable(); + rq_lock(rq); update_rq_clock(rq); update_idle_cpu_load(rq); - raw_spin_unlock_irq(&rq->lock); + rq_unlock(rq); + local_irq_enable(); rebalance_domains(rq, CPU_IDLE); @@ -7359,7 +7364,8 @@ static void task_fork_fair(struct task_s struct rq *rq = this_rq(); unsigned long flags; - raw_spin_lock_irqsave(&rq->lock, flags); + local_irq_save(flags); + rq_lock(rq); update_rq_clock(rq); @@ -7393,7 +7399,8 @@ static void task_fork_fair(struct task_s se->vruntime -= cfs_rq->min_vruntime; - raw_spin_unlock_irqrestore(&rq->lock, flags); + rq_unlock(rq); + local_irq_restore(flags); } /* @@ -7634,9 +7641,9 @@ void unregister_fair_sched_group(struct if (!tg->cfs_rq[cpu]->on_list) return; - raw_spin_lock_irqsave(&rq->lock, flags); + raw_spin_lock_irqsave(&rq->__lock, flags); list_del_leaf_cfs_rq(tg->cfs_rq[cpu]); - raw_spin_unlock_irqrestore(&rq->lock, flags); + raw_spin_unlock_irqrestore(&rq->__lock, flags); } void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq, @@ -7696,13 +7703,16 @@ int sched_group_set_shares(struct task_g se = tg->se[i]; /* Propagate contribution to hierarchy */ - raw_spin_lock_irqsave(&rq->lock, flags); + local_irq_save(flags); + rq_lock(rq); /* Possible calls to update_curr() need rq clock */ update_rq_clock(rq); for_each_sched_entity(se) update_cfs_shares(group_cfs_rq(se)); - raw_spin_unlock_irqrestore(&rq->lock, flags); + + rq_unlock(rq); + local_irq_restore(flags); } done: --- a/kernel/sched/idle_task.c +++ b/kernel/sched/idle_task.c @@ -39,10 +39,10 @@ pick_next_task_idle(struct rq *rq, struc static void dequeue_task_idle(struct rq *rq, struct task_struct *p, int flags) { - raw_spin_unlock_irq(&rq->lock); + raw_spin_unlock_irq(&rq->__lock); printk(KERN_ERR "bad: scheduling from the idle thread!\n"); dump_stack(); - raw_spin_lock_irq(&rq->lock); + raw_spin_lock_irq(&rq->__lock); } static void put_prev_task_idle(struct rq *rq, struct task_struct *prev) --- a/kernel/sched/proc.c +++ b/kernel/sched/proc.c @@ -561,7 +561,7 @@ void update_cpu_load_nohz(void) if (curr_jiffies == this_rq->last_load_update_tick) return; - raw_spin_lock(&this_rq->lock); + raw_spin_lock(&this_rq->__lock); pending_updates = curr_jiffies - this_rq->last_load_update_tick; if (pending_updates) { this_rq->last_load_update_tick = curr_jiffies; @@ -571,7 +571,7 @@ void update_cpu_load_nohz(void) */ __update_cpu_load(this_rq, 0, pending_updates); } - raw_spin_unlock(&this_rq->lock); + raw_spin_unlock(&this_rq->__lock); } #endif /* CONFIG_NO_HZ */ --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -813,7 +813,7 @@ static int do_sched_rt_period_timer(stru struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i); struct rq *rq = rq_of_rt_rq(rt_rq); - raw_spin_lock(&rq->lock); + rq_lock(rq); if (rt_rq->rt_time) { u64 runtime; @@ -846,7 +846,7 @@ static int do_sched_rt_period_timer(stru if (enqueue) sched_rt_rq_enqueue(rt_rq); - raw_spin_unlock(&rq->lock); + rq_unlock(rq); } if (!throttled && (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)) --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -507,7 +507,7 @@ extern struct root_domain def_root_domai */ struct rq { /* runqueue lock: */ - raw_spinlock_t lock; + raw_spinlock_t __lock; /* * nr_running and cpu_load should be in the same cacheline because @@ -528,7 +528,6 @@ struct rq { #ifdef CONFIG_NO_HZ_FULL unsigned long last_sched_tick; #endif - int skip_clock_update; /* capture load from *all* tasks on this cpu: */ struct load_weight load; @@ -558,8 +557,11 @@ struct rq { unsigned long next_balance; struct mm_struct *prev_mm; - u64 clock; - u64 clock_task; + unsigned int clock_seq; + unsigned int clock_stamp; + int skip_clock_update; + u64 __clock; + u64 __clock_task; atomic_t nr_iowait; @@ -635,6 +637,24 @@ struct rq { #endif }; +static inline void rq_lock(struct rq *rq) +{ + raw_spin_lock(&rq->__lock); +#ifdef CONFIG_SCHED_DEBUG_CLOCK + rq->clock_seq++; + barrier(); +#endif +} + +static inline void rq_unlock(struct rq *rq) +{ +#ifdef CONFIG_SCHED_DEBUG_CLOCK + barrier(); + rq->clock_seq++; +#endif + raw_spin_unlock(&rq->__lock); +} + static inline int cpu_of(struct rq *rq) { #ifdef CONFIG_SMP @@ -654,12 +674,26 @@ DECLARE_PER_CPU(struct rq, runqueues); static inline u64 rq_clock(struct rq *rq) { - return rq->clock; +#ifdef CONFIG_SCHED_DEBUG_CLOCK + if (rq->clock_stamp != rq->clock_seq) { + trace_printk("reading invalid rq->clock: %u != %u\n", + rq->clock_stamp, rq->clock_seq); + } +#endif + + return rq->__clock; } static inline u64 rq_clock_task(struct rq *rq) { - return rq->clock_task; +#ifdef CONFIG_SCHED_DEBUG_CLOCK + if (rq->clock_stamp != rq->clock_seq) { + trace_printk("reading invalid rq->clock_task: %u != %u\n", + rq->clock_stamp, rq->clock_seq); + } +#endif + + return rq->__clock_task; } #ifdef CONFIG_NUMA_BALANCING @@ -980,16 +1014,17 @@ static inline void finish_lock_switch(st #endif #ifdef CONFIG_DEBUG_SPINLOCK /* this is a valid case when another task releases the spinlock */ - rq->lock.owner = current; + rq->__lock.owner = current; #endif /* * If we are tracking spinlock dependencies then we have to * fix up the runqueue lock - which gets 'carried over' from * prev into current: */ - spin_acquire(&rq->lock.dep_map, 0, 0, _THIS_IP_); + spin_acquire(&rq->__lock.dep_map, 0, 0, _THIS_IP_); - raw_spin_unlock_irq(&rq->lock); + rq_unlock(rq); + local_irq_enable(); } #else /* __ARCH_WANT_UNLOCKED_CTXSW */ @@ -1003,7 +1038,7 @@ static inline void prepare_lock_switch(s */ next->on_cpu = 1; #endif - raw_spin_unlock(&rq->lock); + rq_unlock(rq); } static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev) @@ -1305,12 +1340,12 @@ static inline void double_rq_lock(struct * reduces latency compared to the unfair variant below. However, it * also adds more overhead and therefore may reduce throughput. */ -static inline int _double_lock_balance(struct rq *this_rq, struct rq *busiest) +static inline int double_lock_balance(struct rq *this_rq, struct rq *busiest) __releases(this_rq->lock) __acquires(busiest->lock) __acquires(this_rq->lock) { - raw_spin_unlock(&this_rq->lock); + raw_spin_unlock(&this_rq->__lock); double_rq_lock(this_rq, busiest); return 1; @@ -1324,22 +1359,22 @@ static inline int _double_lock_balance(s * grant the double lock to lower cpus over higher ids under contention, * regardless of entry order into the function. */ -static inline int _double_lock_balance(struct rq *this_rq, struct rq *busiest) +static inline int double_lock_balance(struct rq *this_rq, struct rq *busiest) __releases(this_rq->lock) __acquires(busiest->lock) __acquires(this_rq->lock) { int ret = 0; - if (unlikely(!raw_spin_trylock(&busiest->lock))) { + if (unlikely(!raw_spin_trylock(&busiest->__lock))) { if (busiest < this_rq) { - raw_spin_unlock(&this_rq->lock); - raw_spin_lock(&busiest->lock); - raw_spin_lock_nested(&this_rq->lock, + raw_spin_unlock(&this_rq->__lock); + raw_spin_lock(&busiest->__lock); + raw_spin_lock_nested(&this_rq->__lock, SINGLE_DEPTH_NESTING); ret = 1; } else - raw_spin_lock_nested(&busiest->lock, + raw_spin_lock_nested(&busiest->__lock, SINGLE_DEPTH_NESTING); } return ret; @@ -1347,25 +1382,11 @@ static inline int _double_lock_balance(s #endif /* CONFIG_PREEMPT */ -/* - * double_lock_balance - lock the busiest runqueue, this_rq is locked already. - */ -static inline int double_lock_balance(struct rq *this_rq, struct rq *busiest) -{ - if (unlikely(!irqs_disabled())) { - /* printk() doesn't work good under rq->lock */ - raw_spin_unlock(&this_rq->lock); - BUG_ON(1); - } - - return _double_lock_balance(this_rq, busiest); -} - static inline void double_unlock_balance(struct rq *this_rq, struct rq *busiest) __releases(busiest->lock) { - raw_spin_unlock(&busiest->lock); - lock_set_subclass(&this_rq->lock.dep_map, 0, _RET_IP_); + raw_spin_unlock(&busiest->__lock); + lock_set_subclass(&this_rq->__lock.dep_map, 0, _RET_IP_); } static inline void double_lock(spinlock_t *l1, spinlock_t *l2) @@ -1407,15 +1428,15 @@ static inline void double_rq_lock(struct { BUG_ON(!irqs_disabled()); if (rq1 == rq2) { - raw_spin_lock(&rq1->lock); + raw_spin_lock(&rq1->__lock); __acquire(rq2->lock); /* Fake it out ;) */ } else { if (rq1 < rq2) { - raw_spin_lock(&rq1->lock); - raw_spin_lock_nested(&rq2->lock, SINGLE_DEPTH_NESTING); + raw_spin_lock(&rq1->__lock); + raw_spin_lock_nested(&rq2->__lock, SINGLE_DEPTH_NESTING); } else { - raw_spin_lock(&rq2->lock); - raw_spin_lock_nested(&rq1->lock, SINGLE_DEPTH_NESTING); + raw_spin_lock(&rq2->__lock); + raw_spin_lock_nested(&rq1->__lock, SINGLE_DEPTH_NESTING); } } } @@ -1430,9 +1451,9 @@ static inline void double_rq_unlock(stru __releases(rq1->lock) __releases(rq2->lock) { - raw_spin_unlock(&rq1->lock); + raw_spin_unlock(&rq1->__lock); if (rq1 != rq2) - raw_spin_unlock(&rq2->lock); + raw_spin_unlock(&rq2->__lock); else __release(rq2->lock); } @@ -1451,7 +1472,7 @@ static inline void double_rq_lock(struct { BUG_ON(!irqs_disabled()); BUG_ON(rq1 != rq2); - raw_spin_lock(&rq1->lock); + raw_spin_lock(&rq1->__lock); __acquire(rq2->lock); /* Fake it out ;) */ } --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -788,6 +788,13 @@ config SCHED_DEBUG that can help debug the scheduler. The runtime overhead of this option is minimal. +config SCHED_DEBUG_CLOCK + bool "Debug rq clock" + depends on SCHED_DEBUG + default n + help + If you say Y here the ftrace output contains debug muck for rq->clock + config SCHEDSTATS bool "Collect scheduler statistics" depends on DEBUG_KERNEL && PROC_FS -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
