timerfd: Manage cancelable timers in timerfd
Peter is concerned about the extra scan of CLOCK_REALTIME_COS in the
timer interrupt. Yes, I did not think about it, because the solution
was so elegant. I didn't like the extra list in timerfd when it was
proposed some time ago, but with a rcu based list the list walk it's
less horrible than the original global lock, which was held over the
list iteration.
Requested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Peter Zijlstra <peterz@infradead.org>
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index eabcbd7..26dd32f 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -78,11 +78,6 @@
.get_time = &ktime_get_boottime,
.resolution = KTIME_LOW_RES,
},
- {
- .index = CLOCK_REALTIME_COS,
- .get_time = &ktime_get_real,
- .resolution = KTIME_LOW_RES,
- },
}
};
@@ -90,7 +85,6 @@
[CLOCK_REALTIME] = HRTIMER_BASE_REALTIME,
[CLOCK_MONOTONIC] = HRTIMER_BASE_MONOTONIC,
[CLOCK_BOOTTIME] = HRTIMER_BASE_BOOTTIME,
- [CLOCK_REALTIME_COS] = HRTIMER_BASE_REALTIME_COS,
};
static inline int hrtimer_clockid_to_base(clockid_t clock_id)
@@ -116,7 +110,6 @@
base->clock_base[HRTIMER_BASE_REALTIME].softirq_time = xtim;
base->clock_base[HRTIMER_BASE_MONOTONIC].softirq_time = mono;
base->clock_base[HRTIMER_BASE_BOOTTIME].softirq_time = boot;
- base->clock_base[HRTIMER_BASE_REALTIME_COS].softirq_time = xtim;
}
/*
@@ -486,8 +479,6 @@
trace_hrtimer_cancel(timer);
}
-static void hrtimer_expire_cancelable(struct hrtimer_cpu_base *cpu_base);
-
/* High resolution timer related functions */
#ifdef CONFIG_HIGH_RES_TIMERS
@@ -663,7 +654,33 @@
return 0;
}
-static void retrigger_next_event(void *arg);
+/*
+ * Retrigger next event is called after clock was set
+ *
+ * Called with interrupts disabled via on_each_cpu()
+ */
+static void retrigger_next_event(void *arg)
+{
+ struct hrtimer_cpu_base *base = &__get_cpu_var(hrtimer_bases);
+ struct timespec realtime_offset, xtim, wtm, sleep;
+
+ if (!hrtimer_hres_active())
+ return;
+
+ /* Optimized out for !HIGH_RES */
+ get_xtime_and_monotonic_and_sleep_offset(&xtim, &wtm, &sleep);
+ set_normalized_timespec(&realtime_offset, -wtm.tv_sec, -wtm.tv_nsec);
+
+ /* Adjust CLOCK_REALTIME offset */
+ raw_spin_lock(&base->lock);
+ base->clock_base[HRTIMER_BASE_REALTIME].offset =
+ timespec_to_ktime(realtime_offset);
+ base->clock_base[HRTIMER_BASE_BOOTTIME].offset =
+ timespec_to_ktime(sleep);
+
+ hrtimer_force_reprogram(base, 0);
+ raw_spin_unlock(&base->lock);
+}
/*
* Switch to high resolution mode
@@ -711,46 +728,11 @@
return 0;
}
static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base) { }
+static inline void retrigger_next_event(void *arg) { }
#endif /* CONFIG_HIGH_RES_TIMERS */
/*
- * Retrigger next event is called after clock was set
- *
- * Called with interrupts disabled via on_each_cpu()
- */
-static void retrigger_next_event(void *arg)
-{
- struct hrtimer_cpu_base *base = &__get_cpu_var(hrtimer_bases);
- struct timespec realtime_offset, xtim, wtm, sleep;
-
- if (!hrtimer_hres_active()) {
- raw_spin_lock(&base->lock);
- hrtimer_expire_cancelable(base);
- raw_spin_unlock(&base->lock);
- return;
- }
-
- /* Optimized out for !HIGH_RES */
- get_xtime_and_monotonic_and_sleep_offset(&xtim, &wtm, &sleep);
- set_normalized_timespec(&realtime_offset, -wtm.tv_sec, -wtm.tv_nsec);
-
- /* Adjust CLOCK_REALTIME offset */
- raw_spin_lock(&base->lock);
- base->clock_base[HRTIMER_BASE_REALTIME].offset =
- timespec_to_ktime(realtime_offset);
- base->clock_base[HRTIMER_BASE_BOOTTIME].offset =
- timespec_to_ktime(sleep);
- base->clock_base[HRTIMER_BASE_REALTIME_COS].offset =
- timespec_to_ktime(realtime_offset);
-
- hrtimer_expire_cancelable(base);
-
- hrtimer_force_reprogram(base, 0);
- raw_spin_unlock(&base->lock);
-}
-
-/*
* Clock realtime was set
*
* Change the offset of the realtime clock vs. the monotonic
@@ -763,8 +745,11 @@
*/
void clock_was_set(void)
{
+#ifdef CONFIG_HIGHRES_TIMERS
/* Retrigger the CPU local events everywhere */
on_each_cpu(retrigger_next_event, NULL, 1);
+#endif
+ timerfd_clock_was_set();
}
/*
@@ -777,6 +762,7 @@
KERN_INFO "hrtimers_resume() called with IRQs enabled!");
retrigger_next_event(NULL);
+ timerfd_clock_was_set();
}
static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
@@ -1240,22 +1226,6 @@
timer->state &= ~HRTIMER_STATE_CALLBACK;
}
-static void hrtimer_expire_cancelable(struct hrtimer_cpu_base *cpu_base)
-{
- struct timerqueue_node *node;
- struct hrtimer_clock_base *base;
- ktime_t now = ktime_get_real();
-
- base = &cpu_base->clock_base[HRTIMER_BASE_REALTIME_COS];
-
- while ((node = timerqueue_getnext(&base->active))) {
- struct hrtimer *timer;
-
- timer = container_of(node, struct hrtimer, node);
- __run_hrtimer(timer, &now);
- }
-}
-
#ifdef CONFIG_HIGH_RES_TIMERS
/*