| Message ID | 1526541403-16380-1-git-send-email-vincent.guittot@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] sched/rt: fix call to cpufreq_update_util | expand |
On Thu, May 17, 2018 at 09:16:43AM +0200, 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> > --- > - v2: > - remove blank line > > kernel/sched/rt.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c > index 7aef6b4..a9f1119 100644 > --- a/kernel/sched/rt.c > +++ b/kernel/sched/rt.c > @@ -1000,9 +1000,6 @@ 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 > @@ -1288,6 +1285,9 @@ 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); > } 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. And talking about throttle; I think we wanted to check rt_queued in that case. How about the below? --- kernel/sched/cpufreq_schedutil.c | 2 +- kernel/sched/rt.c | 24 ++++++++++++++---------- kernel/sched/sched.h | 5 +++++ 3 files changed, 20 insertions(+), 11 deletions(-) diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c index e13df951aca7..1751f9630e49 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 7aef6b4e885a..a1108a7da777 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -979,8 +979,14 @@ static void update_curr_rt(struct rq *rq) if (sched_rt_runtime(rt_rq) != RUNTIME_INF) { raw_spin_lock(&rt_rq->rt_runtime_lock); rt_rq->rt_time += delta_exec; - if (sched_rt_runtime_exceeded(rt_rq)) + if (sched_rt_runtime_exceeded(rt_rq)) { + struct rq *rq = rq_of_rt_rq(rt_rq); + + if (&rq->rt == rt_rq) + cpufreq_update_util(rq, 0); + resched_curr(rq); + } raw_spin_unlock(&rt_rq->rt_runtime_lock); } } @@ -1000,9 +1006,6 @@ 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 @@ -1019,9 +1022,6 @@ enqueue_top_rt_rq(struct rt_rq *rt_rq) 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); } #if defined CONFIG_SMP @@ -1330,6 +1330,8 @@ enqueue_task_rt(struct rq *rq, struct task_struct *p, int flags) if (!task_current(rq, p) && p->nr_cpus_allowed > 1) enqueue_pushable_task(rq, p); + + cpufreq_update_util(rq, 0); } static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags) @@ -1340,6 +1342,8 @@ static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags) dequeue_rt_entity(rt_se, flags); dequeue_pushable_task(rq, p); + + cpufreq_update_util(rq, 0); } /* @@ -1533,6 +1537,9 @@ pick_next_task_rt(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) struct task_struct *p; struct rt_rq *rt_rq = &rq->rt; + if (!rt_rq->rt_queued) + return NULL; + if (need_pull_rt_task(rq, prev)) { /* * This is OK, because current is on_cpu, which avoids it being @@ -1560,9 +1567,6 @@ pick_next_task_rt(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) if (prev->sched_class == &rt_sched_class) update_curr_rt(rq); - if (!rt_rq->rt_queued) - return NULL; - put_prev_task(rq, prev); p = _pick_next_task_rt(rq); diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index c9895d35c5f7..bec7f2eecaf3 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 rq_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 */
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. > > And talking about throttle; I think we wanted to check rt_queued in that > case. Bah, clearly you also want to update on unthrottle.. but I think there's more buggered wrt throtteling.
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 */ -- 2.7.4 > > > > And talking about throttle; I think we wanted to check rt_queued in that > > case. > > Bah, clearly you also want to update on unthrottle.. but I think there's > more buggered wrt throtteling.
Hi Peter, On 17 May 2018 at 22:12, Vincent Guittot <vincent.guittot@linaro.org> wrote: > 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 What is the status for this problem ? The patch below conflict with b29bbbbff0d6 ('sched/cpufreq: always consider blocked FAIR utilization') that has been merged in tip/sched/core Do you want me to rebase it ? Regards, Vincent > > --- > 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 */ > -- > 2.7.4 > > > > > >> > >> > And talking about throttle; I think we wanted to check rt_queued in that >> > case. >> >> Bah, clearly you also want to update on unthrottle.. but I think there's >> more buggered wrt throtteling. > > > >
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 7aef6b4..a9f1119 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1000,9 +1000,6 @@ 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 @@ -1288,6 +1285,9 @@ 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)
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> --- - v2: - remove blank line kernel/sched/rt.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) -- 2.7.4