}
#endif
+/**
+ * fetch_or - perform *ptr |= mask and return old value of *ptr
+ * @ptr: pointer to value
+ * @mask: mask to OR on the value
+ *
+ * cmpxchg based fetch_or, macro so it works for different integer types
+ */
+#ifndef fetch_or
+#define fetch_or(ptr, mask) \
+({ typeof(*(ptr)) __old, __val = *(ptr); \
+ for (;;) { \
+ __old = cmpxchg((ptr), __val, __val | (mask)); \
+ if (__old == __val) \
+ break; \
+ __val = __old; \
+ } \
+ __old; \
+})
+#endif
+
+
#ifdef CONFIG_GENERIC_ATOMIC64
#include <asm-generic/atomic64.h>
#endif
static inline int perf_event_release_kernel(struct perf_event *event) { return 0; }
#endif
-#if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_NO_HZ_FULL)
-extern bool perf_event_can_stop_tick(void);
-#else
-static inline bool perf_event_can_stop_tick(void) { return true; }
-#endif
-
#if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_CPU_SUP_INTEL)
extern void perf_restore_debug_store(void);
#else
void run_posix_cpu_timers(struct task_struct *task);
void posix_cpu_timers_exit(struct task_struct *task);
void posix_cpu_timers_exit_group(struct task_struct *task);
-
-bool posix_cpu_timers_can_stop_tick(struct task_struct *tsk);
-
void set_process_cpu_timer(struct task_struct *task, unsigned int clock_idx,
cputime_t *newval, cputime_t *oldval);
/* Earliest-expiration cache. */
struct task_cputime cputime_expires;
+#ifdef CONFIG_NO_HZ_FULL
+ unsigned long tick_dep_mask;
+#endif
+
struct list_head cpu_timers[3];
struct pid *tty_old_pgrp;
VTIME_SYS,
} vtime_snap_whence;
#endif
+
+#ifdef CONFIG_NO_HZ_FULL
+ unsigned long tick_dep_mask;
+#endif
unsigned long nvcsw, nivcsw; /* context switch counts */
u64 start_time; /* monotonic time in nsec */
u64 real_start_time; /* boot based time in nsec */
#endif
#ifdef CONFIG_NO_HZ_FULL
-extern bool sched_can_stop_tick(void);
extern u64 scheduler_tick_max_deferment(void);
-#else
-static inline bool sched_can_stop_tick(void) { return false; }
#endif
#ifdef CONFIG_SCHED_AUTOGROUP
tick_broadcast_oneshot_control(TICK_BROADCAST_EXIT);
}
+enum tick_dep_bits {
+ TICK_DEP_BIT_POSIX_TIMER = 0,
+ TICK_DEP_BIT_PERF_EVENTS = 1,
+ TICK_DEP_BIT_SCHED = 2,
+ TICK_DEP_BIT_CLOCK_UNSTABLE = 3
+};
+
+#define TICK_DEP_MASK_NONE 0
+#define TICK_DEP_MASK_POSIX_TIMER (1 << TICK_DEP_BIT_POSIX_TIMER)
+#define TICK_DEP_MASK_PERF_EVENTS (1 << TICK_DEP_BIT_PERF_EVENTS)
+#define TICK_DEP_MASK_SCHED (1 << TICK_DEP_BIT_SCHED)
+#define TICK_DEP_MASK_CLOCK_UNSTABLE (1 << TICK_DEP_BIT_CLOCK_UNSTABLE)
+
#ifdef CONFIG_NO_HZ_COMMON
extern int tick_nohz_enabled;
extern int tick_nohz_tick_stopped(void);
return cpumask_any_and(housekeeping_mask, cpu_online_mask);
}
-extern void tick_nohz_full_kick(void);
+extern void tick_nohz_dep_set(enum tick_dep_bits bit);
+extern void tick_nohz_dep_clear(enum tick_dep_bits bit);
+extern void tick_nohz_dep_set_cpu(int cpu, enum tick_dep_bits bit);
+extern void tick_nohz_dep_clear_cpu(int cpu, enum tick_dep_bits bit);
+extern void tick_nohz_dep_set_task(struct task_struct *tsk,
+ enum tick_dep_bits bit);
+extern void tick_nohz_dep_clear_task(struct task_struct *tsk,
+ enum tick_dep_bits bit);
+extern void tick_nohz_dep_set_signal(struct signal_struct *signal,
+ enum tick_dep_bits bit);
+extern void tick_nohz_dep_clear_signal(struct signal_struct *signal,
+ enum tick_dep_bits bit);
+
+/*
+ * The below are tick_nohz_[set,clear]_dep() wrappers that optimize off-cases
+ * on top of static keys.
+ */
+static inline void tick_dep_set(enum tick_dep_bits bit)
+{
+ if (tick_nohz_full_enabled())
+ tick_nohz_dep_set(bit);
+}
+
+static inline void tick_dep_clear(enum tick_dep_bits bit)
+{
+ if (tick_nohz_full_enabled())
+ tick_nohz_dep_clear(bit);
+}
+
+static inline void tick_dep_set_cpu(int cpu, enum tick_dep_bits bit)
+{
+ if (tick_nohz_full_cpu(cpu))
+ tick_nohz_dep_set_cpu(cpu, bit);
+}
+
+static inline void tick_dep_clear_cpu(int cpu, enum tick_dep_bits bit)
+{
+ if (tick_nohz_full_cpu(cpu))
+ tick_nohz_dep_clear_cpu(cpu, bit);
+}
+
+static inline void tick_dep_set_task(struct task_struct *tsk,
+ enum tick_dep_bits bit)
+{
+ if (tick_nohz_full_enabled())
+ tick_nohz_dep_set_task(tsk, bit);
+}
+static inline void tick_dep_clear_task(struct task_struct *tsk,
+ enum tick_dep_bits bit)
+{
+ if (tick_nohz_full_enabled())
+ tick_nohz_dep_clear_task(tsk, bit);
+}
+static inline void tick_dep_set_signal(struct signal_struct *signal,
+ enum tick_dep_bits bit)
+{
+ if (tick_nohz_full_enabled())
+ tick_nohz_dep_set_signal(signal, bit);
+}
+static inline void tick_dep_clear_signal(struct signal_struct *signal,
+ enum tick_dep_bits bit)
+{
+ if (tick_nohz_full_enabled())
+ tick_nohz_dep_clear_signal(signal, bit);
+}
+
extern void tick_nohz_full_kick_cpu(int cpu);
-extern void tick_nohz_full_kick_all(void);
extern void __tick_nohz_task_switch(void);
#else
static inline int housekeeping_any_cpu(void)
static inline bool tick_nohz_full_enabled(void) { return false; }
static inline bool tick_nohz_full_cpu(int cpu) { return false; }
static inline void tick_nohz_full_add_cpus_to(struct cpumask *mask) { }
+
+static inline void tick_dep_set(enum tick_dep_bits bit) { }
+static inline void tick_dep_clear(enum tick_dep_bits bit) { }
+static inline void tick_dep_set_cpu(int cpu, enum tick_dep_bits bit) { }
+static inline void tick_dep_clear_cpu(int cpu, enum tick_dep_bits bit) { }
+static inline void tick_dep_set_task(struct task_struct *tsk,
+ enum tick_dep_bits bit) { }
+static inline void tick_dep_clear_task(struct task_struct *tsk,
+ enum tick_dep_bits bit) { }
+static inline void tick_dep_set_signal(struct signal_struct *signal,
+ enum tick_dep_bits bit) { }
+static inline void tick_dep_clear_signal(struct signal_struct *signal,
+ enum tick_dep_bits bit) { }
+
static inline void tick_nohz_full_kick_cpu(int cpu) { }
-static inline void tick_nohz_full_kick(void) { }
-static inline void tick_nohz_full_kick_all(void) { }
static inline void __tick_nohz_task_switch(void) { }
#endif
);
#ifdef CONFIG_NO_HZ_COMMON
+
+#define TICK_DEP_NAMES \
+ tick_dep_name(NONE) \
+ tick_dep_name(POSIX_TIMER) \
+ tick_dep_name(PERF_EVENTS) \
+ tick_dep_name(SCHED) \
+ tick_dep_name_end(CLOCK_UNSTABLE)
+
+#undef tick_dep_name
+#undef tick_dep_name_end
+
+#define tick_dep_name(sdep) TRACE_DEFINE_ENUM(TICK_DEP_MASK_##sdep);
+#define tick_dep_name_end(sdep) TRACE_DEFINE_ENUM(TICK_DEP_MASK_##sdep);
+
+TICK_DEP_NAMES
+
+#undef tick_dep_name
+#undef tick_dep_name_end
+
+#define tick_dep_name(sdep) { TICK_DEP_MASK_##sdep, #sdep },
+#define tick_dep_name_end(sdep) { TICK_DEP_MASK_##sdep, #sdep }
+
+#define show_tick_dep_name(val) \
+ __print_symbolic(val, TICK_DEP_NAMES)
+
TRACE_EVENT(tick_stop,
- TP_PROTO(int success, char *error_msg),
+ TP_PROTO(int success, int dependency),
- TP_ARGS(success, error_msg),
+ TP_ARGS(success, dependency),
TP_STRUCT__entry(
__field( int , success )
- __string( msg, error_msg )
+ __field( int , dependency )
),
TP_fast_assign(
__entry->success = success;
- __assign_str(msg, error_msg);
+ __entry->dependency = dependency;
),
- TP_printk("success=%s msg=%s", __entry->success ? "yes" : "no", __get_str(msg))
+ TP_printk("success=%d dependency=%s", __entry->success, \
+ show_tick_dep_name(__entry->dependency))
);
#endif
return rotate;
}
-#ifdef CONFIG_NO_HZ_FULL
-bool perf_event_can_stop_tick(void)
-{
- if (atomic_read(&nr_freq_events) ||
- __this_cpu_read(perf_throttled_count))
- return false;
- else
- return true;
-}
-#endif
-
void perf_event_task_tick(void)
{
struct list_head *head = this_cpu_ptr(&active_ctx_list);
__this_cpu_inc(perf_throttled_seq);
throttled = __this_cpu_xchg(perf_throttled_count, 0);
+ tick_dep_clear_cpu(smp_processor_id(), TICK_DEP_BIT_PERF_EVENTS);
list_for_each_entry_safe(ctx, tmp, head, active_ctx_list)
perf_adjust_freq_unthr_context(ctx, throttled);
atomic_dec(&per_cpu(perf_cgroup_events, cpu));
}
+#ifdef CONFIG_NO_HZ_FULL
+static DEFINE_SPINLOCK(nr_freq_lock);
+#endif
+
+static void unaccount_freq_event_nohz(void)
+{
+#ifdef CONFIG_NO_HZ_FULL
+ spin_lock(&nr_freq_lock);
+ if (atomic_dec_and_test(&nr_freq_events))
+ tick_nohz_dep_clear(TICK_DEP_BIT_PERF_EVENTS);
+ spin_unlock(&nr_freq_lock);
+#endif
+}
+
+static void unaccount_freq_event(void)
+{
+ if (tick_nohz_full_enabled())
+ unaccount_freq_event_nohz();
+ else
+ atomic_dec(&nr_freq_events);
+}
+
static void unaccount_event(struct perf_event *event)
{
bool dec = false;
if (event->attr.task)
atomic_dec(&nr_task_events);
if (event->attr.freq)
- atomic_dec(&nr_freq_events);
+ unaccount_freq_event();
if (event->attr.context_switch) {
dec = true;
atomic_dec(&nr_switch_events);
if (unlikely(throttle
&& hwc->interrupts >= max_samples_per_tick)) {
__this_cpu_inc(perf_throttled_count);
+ tick_dep_set_cpu(smp_processor_id(), TICK_DEP_BIT_PERF_EVENTS);
hwc->interrupts = MAX_INTERRUPTS;
perf_log_throttle(event, 0);
- tick_nohz_full_kick();
ret = 1;
}
}
atomic_inc(&per_cpu(perf_cgroup_events, cpu));
}
+/* Freq events need the tick to stay alive (see perf_event_task_tick). */
+static void account_freq_event_nohz(void)
+{
+#ifdef CONFIG_NO_HZ_FULL
+ /* Lock so we don't race with concurrent unaccount */
+ spin_lock(&nr_freq_lock);
+ if (atomic_inc_return(&nr_freq_events) == 1)
+ tick_nohz_dep_set(TICK_DEP_BIT_PERF_EVENTS);
+ spin_unlock(&nr_freq_lock);
+#endif
+}
+
+static void account_freq_event(void)
+{
+ if (tick_nohz_full_enabled())
+ account_freq_event_nohz();
+ else
+ atomic_inc(&nr_freq_events);
+}
+
+
static void account_event(struct perf_event *event)
{
bool inc = false;
atomic_inc(&nr_comm_events);
if (event->attr.task)
atomic_inc(&nr_task_events);
- if (event->attr.freq) {
- if (atomic_inc_return(&nr_freq_events) == 1)
- tick_nohz_full_kick_all();
- }
+ if (event->attr.freq)
+ account_freq_event();
if (event->attr.context_switch) {
atomic_inc(&nr_switch_events);
inc = true;
#include <linux/static_key.h>
#include <linux/workqueue.h>
#include <linux/compiler.h>
+#include <linux/tick.h>
/*
* Scheduler clock - returns current time in nanosec units.
{
if (!sched_clock_stable())
static_key_slow_inc(&__sched_clock_stable);
+
+ tick_dep_clear(TICK_DEP_BIT_CLOCK_UNSTABLE);
}
void set_sched_clock_stable(void)
/* XXX worry about clock continuity */
if (sched_clock_stable())
static_key_slow_dec(&__sched_clock_stable);
+
+ tick_dep_set(TICK_DEP_BIT_CLOCK_UNSTABLE);
}
static DECLARE_WORK(sched_clock_work, __clear_sched_clock_stable);
}
#endif /* CONFIG_SCHED_HRTICK */
-/*
- * cmpxchg based fetch_or, macro so it works for different integer types
- */
-#define fetch_or(ptr, val) \
-({ typeof(*(ptr)) __old, __val = *(ptr); \
- for (;;) { \
- __old = cmpxchg((ptr), __val, __val | (val)); \
- if (__old == __val) \
- break; \
- __val = __old; \
- } \
- __old; \
-})
-
#if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG)
/*
* Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG,
#endif /* CONFIG_NO_HZ_COMMON */
#ifdef CONFIG_NO_HZ_FULL
-bool sched_can_stop_tick(void)
+bool sched_can_stop_tick(struct rq *rq)
{
+ int fifo_nr_running;
+
+ /* Deadline tasks, even if single, need the tick */
+ if (rq->dl.dl_nr_running)
+ return false;
+
/*
- * FIFO realtime policy runs the highest priority task. Other runnable
- * tasks are of a lower priority. The scheduler tick does nothing.
+ * FIFO realtime policy runs the highest priority task (after DEADLINE).
+ * Other runnable tasks are of a lower priority. The scheduler tick
+ * isn't needed.
*/
- if (current->policy == SCHED_FIFO)
+ fifo_nr_running = rq->rt.rt_nr_running - rq->rt.rr_nr_running;
+ if (fifo_nr_running)
return true;
/*
* Round-robin realtime tasks time slice with other tasks at the same
- * realtime priority. Is this task the only one at this priority?
+ * realtime priority.
*/
- if (current->policy == SCHED_RR) {
- struct sched_rt_entity *rt_se = ¤t->rt;
-
- return list_is_singular(&rt_se->run_list);
+ if (rq->rt.rr_nr_running) {
+ if (rq->rt.rr_nr_running == 1)
+ return true;
+ else
+ return false;
}
- /*
- * More than one running task need preemption.
- * nr_running update is assumed to be visible
- * after IPI is sent from wakers.
- */
- if (this_rq()->nr_running > 1)
+ /* Normal multitasking need periodic preemption checks */
+ if (rq->cfs.nr_running > 1)
return false;
return true;
return 1;
}
+static inline
+unsigned int rt_se_rr_nr_running(struct sched_rt_entity *rt_se)
+{
+ struct rt_rq *group_rq = group_rt_rq(rt_se);
+ struct task_struct *tsk;
+
+ if (group_rq)
+ return group_rq->rr_nr_running;
+
+ tsk = rt_task_of(rt_se);
+
+ return (tsk->policy == SCHED_RR) ? 1 : 0;
+}
+
static inline
void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
{
WARN_ON(!rt_prio(prio));
rt_rq->rt_nr_running += rt_se_nr_running(rt_se);
+ rt_rq->rr_nr_running += rt_se_rr_nr_running(rt_se);
inc_rt_prio(rt_rq, prio);
inc_rt_migration(rt_se, rt_rq);
WARN_ON(!rt_prio(rt_se_prio(rt_se)));
WARN_ON(!rt_rq->rt_nr_running);
rt_rq->rt_nr_running -= rt_se_nr_running(rt_se);
+ rt_rq->rr_nr_running -= rt_se_rr_nr_running(rt_se);
dec_rt_prio(rt_rq, rt_se_prio(rt_se));
dec_rt_migration(rt_se, rt_rq);
struct rt_rq {
struct rt_prio_array active;
unsigned int rt_nr_running;
+ unsigned int rr_nr_running;
#if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
struct {
int curr; /* highest queued rt task prio */
extern void init_entity_runnable_average(struct sched_entity *se);
+#ifdef CONFIG_NO_HZ_FULL
+extern bool sched_can_stop_tick(struct rq *rq);
+
+/*
+ * Tick may be needed by tasks in the runqueue depending on their policy and
+ * requirements. If tick is needed, lets send the target an IPI to kick it out of
+ * nohz mode if necessary.
+ */
+static inline void sched_update_tick_dependency(struct rq *rq)
+{
+ int cpu;
+
+ if (!tick_nohz_full_enabled())
+ return;
+
+ cpu = cpu_of(rq);
+
+ if (!tick_nohz_full_cpu(cpu))
+ return;
+
+ if (sched_can_stop_tick(rq))
+ tick_nohz_dep_clear_cpu(cpu, TICK_DEP_BIT_SCHED);
+ else
+ tick_nohz_dep_set_cpu(cpu, TICK_DEP_BIT_SCHED);
+}
+#else
+static inline void sched_update_tick_dependency(struct rq *rq) { }
+#endif
+
static inline void add_nr_running(struct rq *rq, unsigned count)
{
unsigned prev_nr = rq->nr_running;
if (!rq->rd->overload)
rq->rd->overload = true;
#endif
-
-#ifdef CONFIG_NO_HZ_FULL
- if (tick_nohz_full_cpu(rq->cpu)) {
- /*
- * Tick is needed if more than one task runs on a CPU.
- * Send the target an IPI to kick it out of nohz mode.
- *
- * We assume that IPI implies full memory barrier and the
- * new value of rq->nr_running is visible on reception
- * from the target.
- */
- tick_nohz_full_kick_cpu(rq->cpu);
- }
-#endif
}
+
+ sched_update_tick_dependency(rq);
}
static inline void sub_nr_running(struct rq *rq, unsigned count)
{
rq->nr_running -= count;
+ /* Check if we still need preemption */
+ sched_update_tick_dependency(rq);
}
static inline void rq_last_tick_reset(struct rq *rq)
return err;
}
-
/*
* Validate the clockid_t for a new CPU-clock timer, and initialize the timer.
* This is called from sys_timer_create() and do_cpu_nanosleep() with the
cputime_expires->sched_exp = exp;
break;
}
+ if (CPUCLOCK_PERTHREAD(timer->it_clock))
+ tick_dep_set_task(p, TICK_DEP_BIT_POSIX_TIMER);
+ else
+ tick_dep_set_signal(p->signal, TICK_DEP_BIT_POSIX_TIMER);
}
}
return 0;
}
-#ifdef CONFIG_NO_HZ_FULL
-static void nohz_kick_work_fn(struct work_struct *work)
-{
- tick_nohz_full_kick_all();
-}
-
-static DECLARE_WORK(nohz_kick_work, nohz_kick_work_fn);
-
-/*
- * We need the IPIs to be sent from sane process context.
- * The posix cpu timers are always set with irqs disabled.
- */
-static void posix_cpu_timer_kick_nohz(void)
-{
- if (context_tracking_is_enabled())
- schedule_work(&nohz_kick_work);
-}
-
-bool posix_cpu_timers_can_stop_tick(struct task_struct *tsk)
-{
- if (!task_cputime_zero(&tsk->cputime_expires))
- return false;
-
- /* Check if cputimer is running. This is accessed without locking. */
- if (READ_ONCE(tsk->signal->cputimer.running))
- return false;
-
- return true;
-}
-#else
-static inline void posix_cpu_timer_kick_nohz(void) { }
-#endif
-
/*
* Guts of sys_timer_settime for CPU timers.
* This is called with the timer locked and interrupts disabled.
sample_to_timespec(timer->it_clock,
old_incr, &old->it_interval);
}
- if (!ret)
- posix_cpu_timer_kick_nohz();
+
return ret;
}
__group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
}
}
+ if (task_cputime_zero(tsk_expires))
+ tick_dep_clear_task(tsk, TICK_DEP_BIT_POSIX_TIMER);
}
static inline void stop_process_timers(struct signal_struct *sig)
/* Turn off cputimer->running. This is done without locking. */
WRITE_ONCE(cputimer->running, false);
+ tick_dep_clear_signal(sig, TICK_DEP_BIT_POSIX_TIMER);
}
static u32 onecputick;
arm_timer(timer);
unlock_task_sighand(p, &flags);
- /* Kick full dynticks CPUs in case they need to tick on the new timer */
- posix_cpu_timer_kick_nohz();
out:
timer->it_overrun_last = timer->it_overrun;
timer->it_overrun = -1;
}
if (!*newval)
- goto out;
+ return;
*newval += now;
}
tsk->signal->cputime_expires.virt_exp = *newval;
break;
}
-out:
- posix_cpu_timer_kick_nohz();
+
+ tick_dep_set_signal(tsk->signal, TICK_DEP_BIT_POSIX_TIMER);
}
static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
#include <linux/module.h>
#include <linux/irq_work.h>
#include <linux/posix-timers.h>
-#include <linux/perf_event.h>
#include <linux/context_tracking.h>
#include <asm/irq_regs.h>
cpumask_var_t tick_nohz_full_mask;
cpumask_var_t housekeeping_mask;
bool tick_nohz_full_running;
+static unsigned long tick_dep_mask;
-static bool can_stop_full_tick(void)
+static void trace_tick_dependency(unsigned long dep)
+{
+ if (dep & TICK_DEP_MASK_POSIX_TIMER) {
+ trace_tick_stop(0, TICK_DEP_MASK_POSIX_TIMER);
+ return;
+ }
+
+ if (dep & TICK_DEP_MASK_PERF_EVENTS) {
+ trace_tick_stop(0, TICK_DEP_MASK_PERF_EVENTS);
+ return;
+ }
+
+ if (dep & TICK_DEP_MASK_SCHED) {
+ trace_tick_stop(0, TICK_DEP_MASK_SCHED);
+ return;
+ }
+
+ if (dep & TICK_DEP_MASK_CLOCK_UNSTABLE)
+ trace_tick_stop(0, TICK_DEP_MASK_CLOCK_UNSTABLE);
+}
+
+static bool can_stop_full_tick(struct tick_sched *ts)
{
WARN_ON_ONCE(!irqs_disabled());
- if (!sched_can_stop_tick()) {
- trace_tick_stop(0, "more than 1 task in runqueue\n");
+ if (tick_dep_mask) {
+ trace_tick_dependency(tick_dep_mask);
return false;
}
- if (!posix_cpu_timers_can_stop_tick(current)) {
- trace_tick_stop(0, "posix timers running\n");
+ if (ts->tick_dep_mask) {
+ trace_tick_dependency(ts->tick_dep_mask);
return false;
}
- if (!perf_event_can_stop_tick()) {
- trace_tick_stop(0, "perf events running\n");
+ if (current->tick_dep_mask) {
+ trace_tick_dependency(current->tick_dep_mask);
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()) {
- trace_tick_stop(0, "unstable sched clock\n");
- /*
- * Don't allow the user to think they can get
- * full NO_HZ with this machine.
- */
- WARN_ONCE(tick_nohz_full_running,
- "NO_HZ FULL will not work with unstable sched clock");
+ if (current->signal->tick_dep_mask) {
+ trace_tick_dependency(current->signal->tick_dep_mask);
return false;
}
-#endif
return true;
}
-static void nohz_full_kick_work_func(struct irq_work *work)
+static void nohz_full_kick_func(struct irq_work *work)
{
/* Empty, the tick restart happens on tick_nohz_irq_exit() */
}
static DEFINE_PER_CPU(struct irq_work, nohz_full_kick_work) = {
- .func = nohz_full_kick_work_func,
+ .func = nohz_full_kick_func,
};
/*
* This kick, unlike tick_nohz_full_kick_cpu() and tick_nohz_full_kick_all(),
* is NMI safe.
*/
-void tick_nohz_full_kick(void)
+static void tick_nohz_full_kick(void)
{
if (!tick_nohz_full_cpu(smp_processor_id()))
return;
irq_work_queue_on(&per_cpu(nohz_full_kick_work, cpu), cpu);
}
-static void nohz_full_kick_ipi(void *info)
-{
- /* Empty, the tick restart happens on tick_nohz_irq_exit() */
-}
-
/*
* Kick all full dynticks CPUs in order to force these to re-evaluate
* their dependency on the tick and restart it if necessary.
*/
-void tick_nohz_full_kick_all(void)
+static void tick_nohz_full_kick_all(void)
{
+ int cpu;
+
if (!tick_nohz_full_running)
return;
preempt_disable();
- smp_call_function_many(tick_nohz_full_mask,
- nohz_full_kick_ipi, NULL, false);
- tick_nohz_full_kick();
+ for_each_cpu_and(cpu, tick_nohz_full_mask, cpu_online_mask)
+ tick_nohz_full_kick_cpu(cpu);
preempt_enable();
}
+static void tick_nohz_dep_set_all(unsigned long *dep,
+ enum tick_dep_bits bit)
+{
+ unsigned long prev;
+
+ prev = fetch_or(dep, BIT_MASK(bit));
+ if (!prev)
+ tick_nohz_full_kick_all();
+}
+
+/*
+ * Set a global tick dependency. Used by perf events that rely on freq and
+ * by unstable clock.
+ */
+void tick_nohz_dep_set(enum tick_dep_bits bit)
+{
+ tick_nohz_dep_set_all(&tick_dep_mask, bit);
+}
+
+void tick_nohz_dep_clear(enum tick_dep_bits bit)
+{
+ clear_bit(bit, &tick_dep_mask);
+}
+
+/*
+ * Set per-CPU tick dependency. Used by scheduler and perf events in order to
+ * manage events throttling.
+ */
+void tick_nohz_dep_set_cpu(int cpu, enum tick_dep_bits bit)
+{
+ unsigned long prev;
+ struct tick_sched *ts;
+
+ ts = per_cpu_ptr(&tick_cpu_sched, cpu);
+
+ prev = fetch_or(&ts->tick_dep_mask, BIT_MASK(bit));
+ if (!prev) {
+ preempt_disable();
+ /* Perf needs local kick that is NMI safe */
+ if (cpu == smp_processor_id()) {
+ tick_nohz_full_kick();
+ } else {
+ /* Remote irq work not NMI-safe */
+ if (!WARN_ON_ONCE(in_nmi()))
+ tick_nohz_full_kick_cpu(cpu);
+ }
+ preempt_enable();
+ }
+}
+
+void tick_nohz_dep_clear_cpu(int cpu, enum tick_dep_bits bit)
+{
+ struct tick_sched *ts = per_cpu_ptr(&tick_cpu_sched, cpu);
+
+ clear_bit(bit, &ts->tick_dep_mask);
+}
+
+/*
+ * Set a per-task tick dependency. Posix CPU timers need this in order to elapse
+ * per task timers.
+ */
+void tick_nohz_dep_set_task(struct task_struct *tsk, enum tick_dep_bits bit)
+{
+ /*
+ * We could optimize this with just kicking the target running the task
+ * if that noise matters for nohz full users.
+ */
+ tick_nohz_dep_set_all(&tsk->tick_dep_mask, bit);
+}
+
+void tick_nohz_dep_clear_task(struct task_struct *tsk, enum tick_dep_bits bit)
+{
+ clear_bit(bit, &tsk->tick_dep_mask);
+}
+
+/*
+ * Set a per-taskgroup tick dependency. Posix CPU timers need this in order to elapse
+ * per process timers.
+ */
+void tick_nohz_dep_set_signal(struct signal_struct *sig, enum tick_dep_bits bit)
+{
+ tick_nohz_dep_set_all(&sig->tick_dep_mask, bit);
+}
+
+void tick_nohz_dep_clear_signal(struct signal_struct *sig, enum tick_dep_bits bit)
+{
+ clear_bit(bit, &sig->tick_dep_mask);
+}
+
/*
* Re-evaluate the need for the tick as we switch the current task.
* It might need the tick due to per task/process properties:
void __tick_nohz_task_switch(void)
{
unsigned long flags;
+ struct tick_sched *ts;
local_irq_save(flags);
if (!tick_nohz_full_cpu(smp_processor_id()))
goto out;
- if (tick_nohz_tick_stopped() && !can_stop_full_tick())
- tick_nohz_full_kick();
+ ts = this_cpu_ptr(&tick_cpu_sched);
+ if (ts->tick_stopped) {
+ if (current->tick_dep_mask || current->signal->tick_dep_mask)
+ tick_nohz_full_kick();
+ }
out:
local_irq_restore(flags);
}
ts->last_tick = hrtimer_get_expires(&ts->sched_timer);
ts->tick_stopped = 1;
- trace_tick_stop(1, " ");
+ trace_tick_stop(1, TICK_DEP_MASK_NONE);
}
/*
if (!ts->tick_stopped && ts->nohz_mode == NOHZ_MODE_INACTIVE)
return;
- if (can_stop_full_tick())
+ if (can_stop_full_tick(ts))
tick_nohz_stop_sched_tick(ts, ktime_get(), cpu);
else if (ts->tick_stopped)
tick_nohz_restart_sched_tick(ts, ktime_get(), 1);
u64 next_timer;
ktime_t idle_expires;
int do_timer_last;
+ unsigned long tick_dep_mask;
};
extern struct tick_sched *tick_get_tick_sched(int cpu);
projects / mirror_ubuntu-artful-kernel.git / commitdiff