To isolate CPUs (isolate from hrtimers) from sysfs using cpusets, we need some
support from the hrtimer core. i.e. A routine hrtimer_quiesce_cpu() which would
migrate away all the unpinned hrtimers, but shouldn't touch the pinned ones.
This patch creates this routine.
Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
---
include/linux/hrtimer.h | 3 +++
kernel/hrtimer.c | 47 +++++++++++++++++++++++++++++++++++++++--------
2 files changed, 42 insertions(+), 8 deletions(-)
diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index 9fdb67b..0718753 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -350,6 +350,9 @@ DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
/* Exported timer functions: */
+/* To be used from cpusets, only */
+extern void hrtimer_quiesce_cpu(void *cpup);
+
/* Initialize timers: */
extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
enum hrtimer_mode mode);
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 853dd8c..e8cd1db 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -1633,17 +1633,21 @@ static void init_hrtimers_cpu(int cpu)
hrtimer_init_hres(cpu_base);
}
-#ifdef CONFIG_HOTPLUG_CPU
-
+#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_CPUSETS)
static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
- struct hrtimer_clock_base *new_base)
+ struct hrtimer_clock_base *new_base,
+ bool remove_pinned)
{
struct hrtimer *timer;
struct timerqueue_node *node;
+ struct timerqueue_head pinned;
int is_pinned;
+ timerqueue_init_head(&pinned);
+
while ((node = timerqueue_getnext(&old_base->active))) {
timer = container_of(node, struct hrtimer, node);
+
BUG_ON(hrtimer_callback_running(timer));
debug_deactivate(timer);
@@ -1655,6 +1659,10 @@ static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
__remove_hrtimer(timer, HRTIMER_STATE_MIGRATE, 0);
is_pinned = timer->state & HRTIMER_STATE_PINNED;
+ if (!remove_pinned && is_pinned) {
+ timerqueue_add(&pinned, &timer->node);
+ continue;
+ }
/* Check if CPU still has pinned timers */
if (unlikely(WARN(is_pinned,
@@ -1676,18 +1684,24 @@ static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
/* Clear the migration state bit */
timer->state &= ~HRTIMER_STATE_MIGRATE;
}
+
+ /* Re-queue pinned timers for non-hotplug usecase */
+ while ((node = timerqueue_getnext(&pinned))) {
+ timer = container_of(node, struct hrtimer, node);
+
+ timerqueue_del(&pinned, &timer->node);
+ enqueue_hrtimer(timer);
+ timer->state &= ~HRTIMER_STATE_MIGRATE;
+ }
}
-static void migrate_hrtimers(int scpu)
+static void __migrate_hrtimers(int scpu, bool remove_pinned)
{
struct hrtimer_cpu_base *old_base, *new_base;
struct hrtimer_clock_base *clock_base;
unsigned int active_bases;
int i;
- BUG_ON(cpu_online(scpu));
- tick_cancel_sched_timer(scpu);
-
local_irq_disable();
old_base = &per_cpu(hrtimer_bases, scpu);
new_base = &__get_cpu_var(hrtimer_bases);
@@ -1700,7 +1714,8 @@ static void migrate_hrtimers(int scpu)
for_each_active_base(i, clock_base, old_base, active_bases)
migrate_hrtimer_list(clock_base,
- &new_base->clock_base[clock_base->index]);
+ &new_base->clock_base[clock_base->index],
+ remove_pinned);
raw_spin_unlock(&old_base->lock);
raw_spin_unlock(&new_base->lock);
@@ -1709,9 +1724,25 @@ static void migrate_hrtimers(int scpu)
__hrtimer_peek_ahead_timers();
local_irq_enable();
}
+#endif /* CONFIG_HOTPLUG_CPU || CONFIG_CPUSETS */
+#ifdef CONFIG_HOTPLUG_CPU
+static void migrate_hrtimers(int scpu)
+{
+ BUG_ON(cpu_online(scpu));
+ tick_cancel_sched_timer(scpu);
+
+ __migrate_hrtimers(scpu, true);
+}
#endif /* CONFIG_HOTPLUG_CPU */
+#ifdef CONFIG_CPUSETS
+void hrtimer_quiesce_cpu(void *cpup)
+{
+ __migrate_hrtimers(*(int *)cpup, false);
+}
+#endif /* CONFIG_CPUSETS */
+
static int hrtimer_cpu_notify(struct notifier_block *self,
unsigned long action, void *hcpu)
{
--
1.7.12.rc2.18.g61b472e
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