On 17 May 2018 at 06:08, Viresh Kumar viresh.kumar@linaro.org wrote:
On 16-05-18, 20:18, Vincent Guittot wrote:
With commit 8f111bc357aa ("cpufreq/schedutil: Rewrite CPUFREQ_RT support") schedutil governor uses rq->rt.rt_nr_running to detect whether a RT task is currently running on the CPU and to set frequency to max if necessary. cpufreq_update_util() is called in enqueue/dequeue_top_rt_rq() but rq->rt.rt_nr_running as not been updated yet when dequeue_top_rt_rq() is called so schedutil still considers that a RT task is running when the last task is dequeued. The update of rq->rt.rt_nr_running happens later in dequeue_rt_stack()
Fixes: 8f111bc357aa ('cpufreq/schedutil: Rewrite CPUFREQ_RT support') Cc: stable@vger.kernel.org # v4.16+ Signed-off-by: Vincent Guittot vincent.guittot@linaro.org
kernel/sched/rt.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 7aef6b4..6e74d3d 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1001,8 +1001,6 @@ dequeue_top_rt_rq(struct rt_rq *rt_rq) sub_nr_running(rq, rt_rq->rt_nr_running); rt_rq->rt_queued = 0;
Remove this blank line as well ?
Yes good point
/* Kick cpufreq (see the comment in kernel/sched/sched.h). */cpufreq_update_util(rq, 0);}
static void @@ -1288,6 +1286,9 @@ static void dequeue_rt_stack(struct sched_rt_entity *rt_se, unsigned int flags) if (on_rt_rq(rt_se)) __dequeue_rt_entity(rt_se, flags); }
/* Kick cpufreq (see the comment in kernel/sched/sched.h). */cpufreq_update_util(rq_of_rt_rq(rt_rq_of_se(back)), 0);}
static void enqueue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)
2.7.4
-- viresh