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Date: Tue, 17 Jun 2014 16:56:11 +0400
From: Kirill Tkhai <ktkhai@...allels.com>
To: Mike Galbraith <umgwanakikbuti@...il.com>
CC: <tkhai@...dex.ru>, Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"Peter Zijlstra" <peterz@...radead.org>,
Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH 1/2] sched: Rework migrate_tasks()
Hi, Mike,
В Чт, 12/06/2014 в 04:05 +0200, Mike Galbraith пишет:
> 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" <srikar@...ux.vnet.ibm.com>:
> > > >>> * Kirill Tkhai <ktkhai@...allels.com> [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.
thanks for your suggestion and very sorry for the delay in the reply.
This does not decide my problem. I found it's connected with different
thing. My initial assumption was wrong. If we freeze the clock, we should
keep it freezed for all _cpu_down() execution, and it's not good decidion.
I'll send one more series, which fixes individual class .rq_offline().
Regards,
Kirill
> 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: <stable@...r.kernel.org>
> > Signed-off-by: Mike Galbraith <umgwanakikbuti@...il.com>
> > ---
> > 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
>
>
--
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