Le Thursday 17 May 2018 à 11:32:06 (+0200), Peter Zijlstra a écrit :
On Thu, May 17, 2018 at 11:05:30AM +0200, Peter Zijlstra wrote:
Hurm.. I think this is also wrong. See how dequeue_rt_stack() is also called from the enqueue path. Also, nothing calls cpufreq_update_util() on the throttle path now.
Yes I missed the point that rt_entities were dequeued then re-enqueued when a task was either enqueued or dequeued.
That's also means that enqueue_top_rt_rq() is always called when a task is enqueued or dequeued and also when groups are throttled or unthrottled In fact, the only point where it's not called, is when root rt_rq is throttled. So I have prepared the patch below which call cpufreq_update util in enqueue_top_rt_rq() and also when we throttle the root rt_rq. According to the tests I have done , it seems to work for enqueue/dequeue and throttle/unthrottle use cases.
I have re-used your rt_rq_is_runnable() which takes into account rt_queued
--- kernel/sched/cpufreq_schedutil.c | 2 +- kernel/sched/rt.c | 16 ++++++++++------ kernel/sched/sched.h | 5 +++++ 3 files changed, 16 insertions(+), 7 deletions(-)
diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c index e13df95..1751f96 100644 --- a/kernel/sched/cpufreq_schedutil.c +++ b/kernel/sched/cpufreq_schedutil.c @@ -185,7 +185,7 @@ static unsigned long sugov_aggregate_util(struct sugov_cpu *sg_cpu) struct rq *rq = cpu_rq(sg_cpu->cpu); unsigned long util;
- if (rq->rt.rt_nr_running) { + if (rt_rq_is_runnable(&rq->rt)) { util = sg_cpu->max; } else { util = sg_cpu->util_dl; diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 7aef6b4..d6b9517 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -508,8 +508,11 @@ static void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
rt_se = rt_rq->tg->rt_se[cpu];
- if (!rt_se) + if (!rt_se) { dequeue_top_rt_rq(rt_rq); + /* Kick cpufreq (see the comment in kernel/sched/sched.h). */ + cpufreq_update_util(rq_of_rt_rq(rt_rq), 0); + } else if (on_rt_rq(rt_se)) dequeue_rt_entity(rt_se, 0); } @@ -1001,8 +1004,6 @@ dequeue_top_rt_rq(struct rt_rq *rt_rq) sub_nr_running(rq, rt_rq->rt_nr_running); rt_rq->rt_queued = 0;
- /* Kick cpufreq (see the comment in kernel/sched/sched.h). */ - cpufreq_update_util(rq, 0); }
static void @@ -1014,11 +1015,14 @@ enqueue_top_rt_rq(struct rt_rq *rt_rq)
if (rt_rq->rt_queued) return; - if (rt_rq_throttled(rt_rq) || !rt_rq->rt_nr_running) + + if (rt_rq_throttled(rt_rq)) return;
- add_nr_running(rq, rt_rq->rt_nr_running); - rt_rq->rt_queued = 1; + if (rt_rq->rt_nr_running) { + add_nr_running(rq, rt_rq->rt_nr_running); + rt_rq->rt_queued = 1; + }
/* Kick cpufreq (see the comment in kernel/sched/sched.h). */ cpufreq_update_util(rq, 0); diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index c9895d3..bbebcfe 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -609,6 +609,11 @@ struct rt_rq { #endif };
+static inline bool rt_rq_is_runnable(struct rt_rq *rt_rq) +{ + return rt_rq->rt_queued && rt_rq->rt_nr_running; +} + /* Deadline class' related fields in a runqueue */ struct dl_rq { /* runqueue is an rbtree, ordered by deadline */