From: Wanpeng Li <wanpeng...@hotmail.com>

Sometimes update_curr() is called w/o tasks actually running, it is
captured by: 

        u64 delta_exec = rq_clock_task(rq) - curr->se.exec_start;

We should not trigger cpufreq update in this case for rt/deadline
classes, and this patch fix it.

Signed-off-by: Wanpeng Li <wanpeng...@hotmail.com>
---
v1 -> v2:
 * add From: head

 kernel/sched/deadline.c | 8 ++++----
 kernel/sched/rt.c       | 8 ++++----
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index affd97e..8f9b5af 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -717,10 +717,6 @@ static void update_curr_dl(struct rq *rq)
        if (!dl_task(curr) || !on_dl_rq(dl_se))
                return;
 
-       /* Kick cpufreq (see the comment in linux/cpufreq.h). */
-       if (cpu_of(rq) == smp_processor_id())
-               cpufreq_trigger_update(rq_clock(rq));
-
        /*
         * Consumed budget is computed considering the time as
         * observed by schedulable tasks (excluding time spent
@@ -736,6 +732,10 @@ static void update_curr_dl(struct rq *rq)
                return;
        }
 
+       /* kick cpufreq (see the comment in linux/cpufreq.h). */
+       if (cpu_of(rq) == smp_processor_id())
+               cpufreq_trigger_update(rq_clock(rq));
+
        schedstat_set(curr->se.statistics.exec_max,
                      max(curr->se.statistics.exec_max, delta_exec));
 
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index c41ea7a..19e1306 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -953,14 +953,14 @@ static void update_curr_rt(struct rq *rq)
        if (curr->sched_class != &rt_sched_class)
                return;
 
-       /* Kick cpufreq (see the comment in linux/cpufreq.h). */
-       if (cpu_of(rq) == smp_processor_id())
-               cpufreq_trigger_update(rq_clock(rq));
-
        delta_exec = rq_clock_task(rq) - curr->se.exec_start;
        if (unlikely((s64)delta_exec <= 0))
                return;
 
+       /* Kick cpufreq (see the comment in linux/cpufreq.h). */
+       if (cpu_of(rq) == smp_processor_id())
+               cpufreq_trigger_update(rq_clock(rq));
+
        schedstat_set(curr->se.statistics.exec_max,
                      max(curr->se.statistics.exec_max, delta_exec));
 
-- 
1.9.1

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