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-rw-r--r--kernel/hrtimer.c58
-rw-r--r--kernel/sched.c11
-rw-r--r--kernel/sysctl.c8
-rw-r--r--kernel/time/clockevents.c12
-rw-r--r--kernel/time/tick-sched.c7
-rw-r--r--kernel/timer.c51
-rw-r--r--kernel/trace/trace_sysprof.c3
7 files changed, 132 insertions, 18 deletions
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index cb8a15c1958..b675a67c9ac 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -43,6 +43,8 @@
#include <linux/seq_file.h>
#include <linux/err.h>
#include <linux/debugobjects.h>
+#include <linux/sched.h>
+#include <linux/timer.h>
#include <asm/uaccess.h>
@@ -193,12 +195,24 @@ struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer,
* Switch the timer base to the current CPU when possible.
*/
static inline struct hrtimer_clock_base *
-switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base)
+switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base,
+ int pinned)
{
struct hrtimer_clock_base *new_base;
struct hrtimer_cpu_base *new_cpu_base;
+ int cpu, preferred_cpu = -1;
+
+ cpu = smp_processor_id();
+#if defined(CONFIG_NO_HZ) && defined(CONFIG_SMP)
+ if (!pinned && get_sysctl_timer_migration() && idle_cpu(cpu)) {
+ preferred_cpu = get_nohz_load_balancer();
+ if (preferred_cpu >= 0)
+ cpu = preferred_cpu;
+ }
+#endif
- new_cpu_base = &__get_cpu_var(hrtimer_bases);
+again:
+ new_cpu_base = &per_cpu(hrtimer_bases, cpu);
new_base = &new_cpu_base->clock_base[base->index];
if (base != new_base) {
@@ -218,6 +232,40 @@ switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base)
timer->base = NULL;
spin_unlock(&base->cpu_base->lock);
spin_lock(&new_base->cpu_base->lock);
+
+ /* Optimized away for NOHZ=n SMP=n */
+ if (cpu == preferred_cpu) {
+ /* Calculate clock monotonic expiry time */
+#ifdef CONFIG_HIGH_RES_TIMERS
+ ktime_t expires = ktime_sub(hrtimer_get_expires(timer),
+ new_base->offset);
+#else
+ ktime_t expires = hrtimer_get_expires(timer);
+#endif
+
+ /*
+ * Get the next event on target cpu from the
+ * clock events layer.
+ * This covers the highres=off nohz=on case as well.
+ */
+ ktime_t next = clockevents_get_next_event(cpu);
+
+ ktime_t delta = ktime_sub(expires, next);
+
+ /*
+ * We do not migrate the timer when it is expiring
+ * before the next event on the target cpu because
+ * we cannot reprogram the target cpu hardware and
+ * we would cause it to fire late.
+ */
+ if (delta.tv64 < 0) {
+ cpu = smp_processor_id();
+ spin_unlock(&new_base->cpu_base->lock);
+ spin_lock(&base->cpu_base->lock);
+ timer->base = base;
+ goto again;
+ }
+ }
timer->base = new_base;
}
return new_base;
@@ -235,7 +283,7 @@ lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
return base;
}
-# define switch_hrtimer_base(t, b) (b)
+# define switch_hrtimer_base(t, b, p) (b)
#endif /* !CONFIG_SMP */
@@ -907,9 +955,9 @@ int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
ret = remove_hrtimer(timer, base);
/* Switch the timer base, if necessary: */
- new_base = switch_hrtimer_base(timer, base);
+ new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED);
- if (mode == HRTIMER_MODE_REL) {
+ if (mode & HRTIMER_MODE_REL) {
tim = ktime_add_safe(tim, new_base->get_time());
/*
* CONFIG_TIME_LOW_RES is a temporary way for architectures
diff --git a/kernel/sched.c b/kernel/sched.c
index 8ec9d13140b..8fb88a906aa 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -240,7 +240,7 @@ static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
hard = hrtimer_get_expires(&rt_b->rt_period_timer);
delta = ktime_to_ns(ktime_sub(hard, soft));
__hrtimer_start_range_ns(&rt_b->rt_period_timer, soft, delta,
- HRTIMER_MODE_ABS, 0);
+ HRTIMER_MODE_ABS_PINNED, 0);
}
spin_unlock(&rt_b->rt_runtime_lock);
}
@@ -1155,7 +1155,7 @@ static __init void init_hrtick(void)
static void hrtick_start(struct rq *rq, u64 delay)
{
__hrtimer_start_range_ns(&rq->hrtick_timer, ns_to_ktime(delay), 0,
- HRTIMER_MODE_REL, 0);
+ HRTIMER_MODE_REL_PINNED, 0);
}
static inline void init_hrtick(void)
@@ -4397,6 +4397,11 @@ static struct {
.load_balancer = ATOMIC_INIT(-1),
};
+int get_nohz_load_balancer(void)
+{
+ return atomic_read(&nohz.load_balancer);
+}
+
#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
/**
* lowest_flag_domain - Return lowest sched_domain containing flag.
@@ -9029,6 +9034,8 @@ void __init sched_init_smp(void)
}
#endif /* CONFIG_SMP */
+const_debug unsigned int sysctl_timer_migration = 1;
+
int in_sched_functions(unsigned long addr)
{
return in_lock_functions(addr) ||
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index ce664f98e3f..0e51a35a448 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -328,6 +328,14 @@ static struct ctl_table kern_table[] = {
.mode = 0644,
.proc_handler = &proc_dointvec,
},
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "timer_migration",
+ .data = &sysctl_timer_migration,
+ .maxlen = sizeof(unsigned int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec,
+ },
#endif
{
.ctl_name = CTL_UNNUMBERED,
diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index 3948fa644a2..1ad6dd46111 100644
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -18,6 +18,7 @@
#include <linux/notifier.h>
#include <linux/smp.h>
#include <linux/sysdev.h>
+#include <linux/tick.h>
/* The registered clock event devices */
static LIST_HEAD(clockevent_devices);
@@ -253,4 +254,15 @@ void clockevents_notify(unsigned long reason, void *arg)
spin_unlock(&clockevents_lock);
}
EXPORT_SYMBOL_GPL(clockevents_notify);
+
+ktime_t clockevents_get_next_event(int cpu)
+{
+ struct tick_device *td;
+ struct clock_event_device *dev;
+
+ td = &per_cpu(tick_cpu_device, cpu);
+ dev = td->evtdev;
+
+ return dev->next_event;
+}
#endif
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index d3f1ef4d5cb..2aff39c6f10 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -349,7 +349,7 @@ void tick_nohz_stop_sched_tick(int inidle)
if (ts->nohz_mode == NOHZ_MODE_HIGHRES) {
hrtimer_start(&ts->sched_timer, expires,
- HRTIMER_MODE_ABS);
+ HRTIMER_MODE_ABS_PINNED);
/* Check, if the timer was already in the past */
if (hrtimer_active(&ts->sched_timer))
goto out;
@@ -395,7 +395,7 @@ static void tick_nohz_restart(struct tick_sched *ts, ktime_t now)
if (ts->nohz_mode == NOHZ_MODE_HIGHRES) {
hrtimer_start_expires(&ts->sched_timer,
- HRTIMER_MODE_ABS);
+ HRTIMER_MODE_ABS_PINNED);
/* Check, if the timer was already in the past */
if (hrtimer_active(&ts->sched_timer))
break;
@@ -698,7 +698,8 @@ void tick_setup_sched_timer(void)
for (;;) {
hrtimer_forward(&ts->sched_timer, now, tick_period);
- hrtimer_start_expires(&ts->sched_timer, HRTIMER_MODE_ABS);
+ hrtimer_start_expires(&ts->sched_timer,
+ HRTIMER_MODE_ABS_PINNED);
/* Check, if the timer was already in the past */
if (hrtimer_active(&ts->sched_timer))
break;
diff --git a/kernel/timer.c b/kernel/timer.c
index faf2db897de..54d3912f8ca 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -38,6 +38,7 @@
#include <linux/tick.h>
#include <linux/kallsyms.h>
#include <linux/perf_counter.h>
+#include <linux/sched.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>
@@ -605,13 +606,12 @@ static struct tvec_base *lock_timer_base(struct timer_list *timer,
}
static inline int
-__mod_timer(struct timer_list *timer, unsigned long expires, bool pending_only)
+__mod_timer(struct timer_list *timer, unsigned long expires,
+ bool pending_only, int pinned)
{
struct tvec_base *base, *new_base;
unsigned long flags;
- int ret;
-
- ret = 0;
+ int ret = 0 , cpu;
timer_stats_timer_set_start_info(timer);
BUG_ON(!timer->function);
@@ -630,6 +630,18 @@ __mod_timer(struct timer_list *timer, unsigned long expires, bool pending_only)
new_base = __get_cpu_var(tvec_bases);
+ cpu = smp_processor_id();
+
+#if defined(CONFIG_NO_HZ) && defined(CONFIG_SMP)
+ if (!pinned && get_sysctl_timer_migration() && idle_cpu(cpu)) {
+ int preferred_cpu = get_nohz_load_balancer();
+
+ if (preferred_cpu >= 0)
+ cpu = preferred_cpu;
+ }
+#endif
+ new_base = per_cpu(tvec_bases, cpu);
+
if (base != new_base) {
/*
* We are trying to schedule the timer on the local CPU.
@@ -669,7 +681,7 @@ out_unlock:
*/
int mod_timer_pending(struct timer_list *timer, unsigned long expires)
{
- return __mod_timer(timer, expires, true);
+ return __mod_timer(timer, expires, true, TIMER_NOT_PINNED);
}
EXPORT_SYMBOL(mod_timer_pending);
@@ -703,11 +715,33 @@ int mod_timer(struct timer_list *timer, unsigned long expires)
if (timer->expires == expires && timer_pending(timer))
return 1;
- return __mod_timer(timer, expires, false);
+ return __mod_timer(timer, expires, false, TIMER_NOT_PINNED);
}
EXPORT_SYMBOL(mod_timer);
/**
+ * mod_timer_pinned - modify a timer's timeout
+ * @timer: the timer to be modified
+ * @expires: new timeout in jiffies
+ *
+ * mod_timer_pinned() is a way to update the expire field of an
+ * active timer (if the timer is inactive it will be activated)
+ * and not allow the timer to be migrated to a different CPU.
+ *
+ * mod_timer_pinned(timer, expires) is equivalent to:
+ *
+ * del_timer(timer); timer->expires = expires; add_timer(timer);
+ */
+int mod_timer_pinned(struct timer_list *timer, unsigned long expires)
+{
+ if (timer->expires == expires && timer_pending(timer))
+ return 1;
+
+ return __mod_timer(timer, expires, false, TIMER_PINNED);
+}
+EXPORT_SYMBOL(mod_timer_pinned);
+
+/**
* add_timer - start a timer
* @timer: the timer to be added
*
@@ -1017,6 +1051,9 @@ cascade:
index = slot = timer_jiffies & TVN_MASK;
do {
list_for_each_entry(nte, varp->vec + slot, entry) {
+ if (tbase_get_deferrable(nte->base))
+ continue;
+
found = 1;
if (time_before(nte->expires, expires))
expires = nte->expires;
@@ -1307,7 +1344,7 @@ signed long __sched schedule_timeout(signed long timeout)
expire = timeout + jiffies;
setup_timer_on_stack(&timer, process_timeout, (unsigned long)current);
- __mod_timer(&timer, expire, false);
+ __mod_timer(&timer, expire, false, TIMER_NOT_PINNED);
schedule();
del_singleshot_timer_sync(&timer);
diff --git a/kernel/trace/trace_sysprof.c b/kernel/trace/trace_sysprof.c
index e04b76cc238..f6693969287 100644
--- a/kernel/trace/trace_sysprof.c
+++ b/kernel/trace/trace_sysprof.c
@@ -203,7 +203,8 @@ static void start_stack_timer(void *unused)
hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
hrtimer->function = stack_trace_timer_fn;
- hrtimer_start(hrtimer, ns_to_ktime(sample_period), HRTIMER_MODE_REL);
+ hrtimer_start(hrtimer, ns_to_ktime(sample_period),
+ HRTIMER_MODE_REL_PINNED);
}
static void start_stack_timers(void)
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-11-16 18:23:19 +0000