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nohz: Implement full dynticks kick 

Implement the full dynticks kick that is performed from
IPIs sent by various subsystems (scheduler, posix timers, ...)
when they want to notify about a new event that may
reconsider the dependency on the tick.

Most of the time, such an event end up restarting the tick.

(Part of the design with subsystems providing *_can_stop_tick()
helpers suggested by Peter Zijlstra a while ago).

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>
wifi-calibration
Frederic Weisbecker 2013-04-20 15:43:57 +02:00
parent ff442c51f6
commit 9014c45d9e
1 changed files with 38 additions and 4 deletions
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42
kernel/time/tick-sched.c
View File

@ -21,6 +21,8 @@
#include <linux/sched.h>
#include <linux/module.h>
#include <linux/irq_work.h>
#include <linux/posix-timers.h>
#include <linux/perf_event.h>
#include <asm/irq_regs.h>
@ -147,16 +149,48 @@ static void tick_sched_handle(struct tick_sched *ts, struct pt_regs *regs)
static cpumask_var_t nohz_full_mask;
bool have_nohz_full_mask;
static bool can_stop_full_tick(void)
{
WARN_ON_ONCE(!irqs_disabled());
if (!sched_can_stop_tick())
return false;
if (!posix_cpu_timers_can_stop_tick(current))
return false;
if (!perf_event_can_stop_tick())
return false;
/* sched_clock_tick() needs us? */
#ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
/*
* TODO: kick full dynticks CPUs when
* sched_clock_stable is set.
*/
if (!sched_clock_stable)
return false;
#endif
return true;
}
static void tick_nohz_restart_sched_tick(struct tick_sched *ts, ktime_t now);
/*
* Re-evaluate the need for the tick on the current CPU
* and restart it if necessary.
*/
void tick_nohz_full_check(void)
{
/*
* STUB for now, will be filled with the full tick stop/restart
* infrastructure patches
*/
struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
if (tick_nohz_full_cpu(smp_processor_id())) {
if (ts->tick_stopped && !is_idle_task(current)) {
if (!can_stop_full_tick())
tick_nohz_restart_sched_tick(ts, ktime_get());
}
}
}
static void nohz_full_kick_work_func(struct irq_work *work)