To isolate CPUs (isolate from timers) from sysfs using cpusets, we need some
support from the timer core. i.e. A routine timer_quiesce_cpu() which would
migrate away all the unpinned timers, but shouldn't touch the pinned ones.
This patch creates this routine.
Signed-off-by: Viresh Kumar <viresh.ku...@linaro.org>
---
include/linux/timer.h | 3 +++
kernel/timer.c | 54 ++++++++++++++++++++++++++++++++++++++++-----------
2 files changed, 46 insertions(+), 11 deletions(-)
diff --git a/include/linux/timer.h b/include/linux/timer.h
index 2962403..1588a4f 100644
--- a/include/linux/timer.h
+++ b/include/linux/timer.h
@@ -196,6 +196,9 @@ extern void set_timer_slack(struct timer_list *time, int
slack_hz);
*/
extern unsigned long get_next_timer_interrupt(unsigned long now);
+/* To be used from cpusets, only */
+extern void timer_quiesce_cpu(void *cpup);
+
/*
* Timer-statistics info:
*/
diff --git a/kernel/timer.c b/kernel/timer.c
index 6c3a371..4676a07 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -1602,18 +1602,27 @@ static int init_timers_cpu(int cpu)
return 0;
}
-#ifdef CONFIG_HOTPLUG_CPU
-static void migrate_timer_list(struct tvec_base *new_base, struct list_head
*head)
+#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_CPUSETS)
+static void migrate_timer_list(struct tvec_base *new_base,
+ struct list_head *head, bool remove_pinned)
{
struct timer_list *timer;
+ struct list_head pinned_list;
int is_pinned;
+ INIT_LIST_HEAD(&pinned_list);
+
while (!list_empty(head)) {
timer = list_first_entry(head, struct timer_list, entry);
- /* We ignore the accounting on the dying cpu */
- detach_timer(timer, false);
is_pinned = tbase_get_pinned(timer->base);
+ if (!remove_pinned && is_pinned) {
+ list_move_tail(&timer->entry, &pinned_list);
+ continue;
+ } else {
+ /* We ignore the accounting on the dying cpu */
+ detach_timer(timer, false);
+ }
/* Check if CPU still has pinned timers */
if (unlikely(WARN(is_pinned,
@@ -1624,15 +1633,18 @@ static void migrate_timer_list(struct tvec_base
*new_base, struct list_head *hea
timer_set_base(timer, new_base);
internal_add_timer(new_base, timer);
}
+
+ if (!list_empty(&pinned_list))
+ list_splice_tail(&pinned_list, head);
}
-static void migrate_timers(int cpu)
+/* Migrate timers from 'cpu' to this_cpu */
+static void __migrate_timers(int cpu, bool remove_pinned)
{
struct tvec_base *old_base;
struct tvec_base *new_base;
int i;
- BUG_ON(cpu_online(cpu));
old_base = per_cpu(tvec_bases, cpu);
new_base = get_cpu_var(tvec_bases);
/*
@@ -1645,20 +1657,40 @@ static void migrate_timers(int cpu)
BUG_ON(old_base->running_timer);
for (i = 0; i < TVR_SIZE; i++)
- migrate_timer_list(new_base, old_base->tv1.vec + i);
+ migrate_timer_list(new_base, old_base->tv1.vec + i,
+ remove_pinned);
for (i = 0; i < TVN_SIZE; i++) {
- migrate_timer_list(new_base, old_base->tv2.vec + i);
- migrate_timer_list(new_base, old_base->tv3.vec + i);
- migrate_timer_list(new_base, old_base->tv4.vec + i);
- migrate_timer_list(new_base, old_base->tv5.vec + i);
+ migrate_timer_list(new_base, old_base->tv2.vec + i,
+ remove_pinned);
+ migrate_timer_list(new_base, old_base->tv3.vec + i,
+ remove_pinned);
+ migrate_timer_list(new_base, old_base->tv4.vec + i,
+ remove_pinned);
+ migrate_timer_list(new_base, old_base->tv5.vec + i,
+ remove_pinned);
}
spin_unlock(&old_base->lock);
spin_unlock_irq(&new_base->lock);
put_cpu_var(tvec_bases);
}
+#endif /* CONFIG_HOTPLUG_CPU || CONFIG_CPUSETS */
+
+#ifdef CONFIG_HOTPLUG_CPU
+static void migrate_timers(int cpu)
+{
+ BUG_ON(cpu_online(cpu));
+ __migrate_timers(cpu, true);
+}
#endif /* CONFIG_HOTPLUG_CPU */
+#ifdef CONFIG_CPUSETS
+void timer_quiesce_cpu(void *cpup)
+{
+ __migrate_timers(*(int *)cpup, false);
+}
+#endif /* CONFIG_CPUSETS */
+
static int timer_cpu_notify(struct notifier_block *self,
unsigned long action, void *hcpu)
{
--
1.7.12.rc2.18.g61b472e
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