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nohz: Prepare to stop the tick on irq exit 

Interrupt exit is a natural place to stop the tick: it happens
after all events happening before and during the irq which
are liable to update the dependency on the tick occured. Also
it makes sure that any check on tick dependency is well ordered
against dynticks kick IPIs.

Bring in the infrastructure that performs the tick dependency
checks on irq exit and shut it down if these checks show that we
can do it safely.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Frederic Weisbecker 2013-04-20 16:40:31 +02:00
parent 9014c45d9e
commit 5811d9963e
1 changed files with 25 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
kernel/time/tick-sched.c
View File

@ -647,6 +647,24 @@ out:
return ret;
}
static void tick_nohz_full_stop_tick(struct tick_sched *ts)
{
#ifdef CONFIG_NO_HZ_FULL
int cpu = smp_processor_id();
if (!tick_nohz_full_cpu(cpu) || is_idle_task(current))
return;
if (!ts->tick_stopped && ts->nohz_mode == NOHZ_MODE_INACTIVE)
return;
if (!can_stop_full_tick())
return;
tick_nohz_stop_sched_tick(ts, ktime_get(), cpu);
#endif
}
static bool can_stop_idle_tick(int cpu, struct tick_sched *ts)
{
/*
@ -773,12 +791,13 @@ void tick_nohz_irq_exit(void)
{
struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
if (!ts->inidle)
return;
/* Cancel the timer because CPU already waken up from the C-states*/
menu_hrtimer_cancel();
__tick_nohz_idle_enter(ts);
if (ts->inidle) {
/* Cancel the timer because CPU already waken up from the C-states*/
menu_hrtimer_cancel();
__tick_nohz_idle_enter(ts);
} else {
tick_nohz_full_stop_tick(ts);
}
}
/**