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