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Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (64 commits)
  cpu: Export cpu_up()
  rcu: Apply ACCESS_ONCE() to rcu_boost() return value
  Revert "rcu: Permit rt_mutex_unlock() with irqs disabled"
  docs: Additional LWN links to RCU API
  rcu: Augment rcu_batch_end tracing for idle and callback state
  rcu: Add rcutorture tests for srcu_read_lock_raw()
  rcu: Make rcutorture test for hotpluggability before offlining CPUs
  driver-core/cpu: Expose hotpluggability to the rest of the kernel
  rcu: Remove redundant rcu_cpu_stall_suppress declaration
  rcu: Adaptive dyntick-idle preparation
  rcu: Keep invoking callbacks if CPU otherwise idle
  rcu: Irq nesting is always 0 on rcu_enter_idle_common
  rcu: Don't check irq nesting from rcu idle entry/exit
  rcu: Permit dyntick-idle with callbacks pending
  rcu: Document same-context read-side constraints
  rcu: Identify dyntick-idle CPUs on first force_quiescent_state() pass
  rcu: Remove dynticks false positives and RCU failures
  rcu: Reduce latency of rcu_prepare_for_idle()
  rcu: Eliminate RCU_FAST_NO_HZ grace-period hang
  rcu: Avoid needlessly IPIing CPUs at GP end
  ...
This commit is contained in:
Linus Torvalds
2012-01-06 08:02:40 -08:00
parent 1483b38235 919b83452b
commit 423d091dfe
58 changed files with 1520 additions and 415 deletions
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97
kernel/time/tick-sched.c
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@@ -275,42 +275,17 @@ u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time)
}
EXPORT_SYMBOL_GPL(get_cpu_iowait_time_us);
/**
* tick_nohz_stop_sched_tick - stop the idle tick from the idle task
*
* When the next event is more than a tick into the future, stop the idle tick
* Called either from the idle loop or from irq_exit() when an idle period was
* just interrupted by an interrupt which did not cause a reschedule.
*/
void tick_nohz_stop_sched_tick(int inidle)
static void tick_nohz_stop_sched_tick(struct tick_sched *ts)
{
unsigned long seq, last_jiffies, next_jiffies, delta_jiffies, flags;
struct tick_sched *ts;
unsigned long seq, last_jiffies, next_jiffies, delta_jiffies;
ktime_t last_update, expires, now;
struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev;
u64 time_delta;
int cpu;
local_irq_save(flags);
cpu = smp_processor_id();
ts = &per_cpu(tick_cpu_sched, cpu);
/*
* Call to tick_nohz_start_idle stops the last_update_time from being
* updated. Thus, it must not be called in the event we are called from
* irq_exit() with the prior state different than idle.
*/
if (!inidle && !ts->inidle)
goto end;
/*
* Set ts->inidle unconditionally. Even if the system did not
* switch to NOHZ mode the cpu frequency governers rely on the
* update of the idle time accounting in tick_nohz_start_idle().
*/
ts->inidle = 1;
now = tick_nohz_start_idle(cpu, ts);
/*
@@ -326,10 +301,10 @@ void tick_nohz_stop_sched_tick(int inidle)
}
if (unlikely(ts->nohz_mode == NOHZ_MODE_INACTIVE))
goto end;
return;
if (need_resched())
goto end;
return;
if (unlikely(local_softirq_pending() && cpu_online(cpu))) {
static int ratelimit;
@@ -339,7 +314,7 @@ void tick_nohz_stop_sched_tick(int inidle)
(unsigned int) local_softirq_pending());
ratelimit++;
}
goto end;
return;
}
ts->idle_calls++;
@@ -434,7 +409,6 @@ void tick_nohz_stop_sched_tick(int inidle)
ts->idle_tick = hrtimer_get_expires(&ts->sched_timer);
ts->tick_stopped = 1;
ts->idle_jiffies = last_jiffies;
rcu_enter_nohz();
}
ts->idle_sleeps++;
@@ -472,8 +446,56 @@ out:
ts->next_jiffies = next_jiffies;
ts->last_jiffies = last_jiffies;
ts->sleep_length = ktime_sub(dev->next_event, now);
end:
local_irq_restore(flags);
}
/**
* tick_nohz_idle_enter - stop the idle tick from the idle task
*
* When the next event is more than a tick into the future, stop the idle tick
* Called when we start the idle loop.
*
* The arch is responsible of calling:
*
* - rcu_idle_enter() after its last use of RCU before the CPU is put
* to sleep.
* - rcu_idle_exit() before the first use of RCU after the CPU is woken up.
*/
void tick_nohz_idle_enter(void)
{
struct tick_sched *ts;
WARN_ON_ONCE(irqs_disabled());
local_irq_disable();
ts = &__get_cpu_var(tick_cpu_sched);
/*
* set ts->inidle unconditionally. even if the system did not
* switch to nohz mode the cpu frequency governers rely on the
* update of the idle time accounting in tick_nohz_start_idle().
*/
ts->inidle = 1;
tick_nohz_stop_sched_tick(ts);
local_irq_enable();
}
/**
* tick_nohz_irq_exit - update next tick event from interrupt exit
*
* When an interrupt fires while we are idle and it doesn't cause
* a reschedule, it may still add, modify or delete a timer, enqueue
* an RCU callback, etc...
* So we need to re-calculate and reprogram the next tick event.
*/
void tick_nohz_irq_exit(void)
{
struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
if (!ts->inidle)
return;
tick_nohz_stop_sched_tick(ts);
}
/**
@@ -515,11 +537,13 @@ static void tick_nohz_restart(struct tick_sched *ts, ktime_t now)
}
/**
* tick_nohz_restart_sched_tick - restart the idle tick from the idle task
* tick_nohz_idle_exit - restart the idle tick from the idle task
*
* Restart the idle tick when the CPU is woken up from idle
* This also exit the RCU extended quiescent state. The CPU
* can use RCU again after this function is called.
*/
void tick_nohz_restart_sched_tick(void)
void tick_nohz_idle_exit(void)
{
int cpu = smp_processor_id();
struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
@@ -529,6 +553,7 @@ void tick_nohz_restart_sched_tick(void)
ktime_t now;
local_irq_disable();
if (ts->idle_active || (ts->inidle && ts->tick_stopped))
now = ktime_get();
@@ -543,8 +568,6 @@ void tick_nohz_restart_sched_tick(void)
ts->inidle = 0;
rcu_exit_nohz();
/* Update jiffies first */
select_nohz_load_balancer(0);
tick_do_update_jiffies64(now);