Implementing one new API wake_up_if_idle(), which is used to
wake up the idle CPU.
Suggested-by: Andy Lutomirski <l...@amacapital.net>
Signed-off-by: Chuansheng Liu <chuansheng....@intel.com>
---
include/linux/sched.h | 1 +
kernel/sched/core.c | 19 +++++++++++++++++++
2 files changed, 20 insertions(+)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 857ba40..3f89ac1 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1024,6 +1024,7 @@ struct sched_domain_topology_level {
extern struct sched_domain_topology_level *sched_domain_topology;
extern void set_sched_topology(struct sched_domain_topology_level *tl);
+extern void wake_up_if_idle(int cpu);
#ifdef CONFIG_SCHED_DEBUG
# define SD_INIT_NAME(type) .name = #type
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 1211575..b818548 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1620,6 +1620,25 @@ static void ttwu_queue_remote(struct task_struct *p, int
cpu)
}
}
+void wake_up_if_idle(int cpu)
+{
+ struct rq *rq = cpu_rq(cpu);
+ unsigned long flags;
+
+ if (!is_idle_task(rq->curr))
+ return;
+
+ if (set_nr_if_polling(rq->idle)) {
+ trace_sched_wake_idle_without_ipi(cpu);
+ } else {
+ raw_spin_lock_irqsave(&rq->lock, flags);
+ if (is_idle_task(rq->curr))
+ smp_send_reschedule(cpu);
+ /* Else cpu is not in idle, do nothing here */
+ raw_spin_unlock_irqrestore(&rq->lock, flags);
+ }
+}
+
bool cpus_share_cache(int this_cpu, int that_cpu)
{
return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
--
1.7.9.5
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