Messages in this thread | | | From | Vincent Guittot <> | Date | Wed, 9 Dec 2015 09:50:27 +0100 | Subject | Re: [RFCv6 PATCH 09/10] sched: deadline: use deadline bandwidth in scale_rt_capacity |
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adding Lucas
On 9 December 2015 at 07:19, Steve Muckle <steve.muckle@linaro.org> wrote: > From: Vincent Guittot <vincent.guittot@linaro.org> > > Instead of monitoring the exec time of deadline tasks to evaluate the > CPU capacity consumed by deadline scheduler class, we can directly > calculate it thanks to the sum of utilization of deadline tasks on the > CPU. We can remove deadline tasks from rt_avg metric and directly use > the average bandwidth of deadline scheduler in scale_rt_capacity. > > Based in part on a similar patch from Luca Abeni <luca.abeni@unitn.it>. > > Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> > Signed-off-by: Steve Muckle <smuckle@linaro.org> > --- > kernel/sched/deadline.c | 33 +++++++++++++++++++++++++++++++-- > kernel/sched/fair.c | 8 ++++++++ > kernel/sched/sched.h | 2 ++ > 3 files changed, 41 insertions(+), 2 deletions(-) > > diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c > index 8b0a15e..9d9eb50 100644 > --- a/kernel/sched/deadline.c > +++ b/kernel/sched/deadline.c > @@ -43,6 +43,24 @@ static inline int on_dl_rq(struct sched_dl_entity *dl_se) > return !RB_EMPTY_NODE(&dl_se->rb_node); > } > > +static void add_average_bw(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) > +{ > + u64 se_bw = dl_se->dl_bw; > + > + dl_rq->avg_bw += se_bw; > +} > + > +static void clear_average_bw(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) > +{ > + u64 se_bw = dl_se->dl_bw; > + > + dl_rq->avg_bw -= se_bw; > + if (dl_rq->avg_bw < 0) { > + WARN_ON(1); > + dl_rq->avg_bw = 0; > + } > +} > + > static inline int is_leftmost(struct task_struct *p, struct dl_rq *dl_rq) > { > struct sched_dl_entity *dl_se = &p->dl; > @@ -494,6 +512,9 @@ static void update_dl_entity(struct sched_dl_entity *dl_se, > struct dl_rq *dl_rq = dl_rq_of_se(dl_se); > struct rq *rq = rq_of_dl_rq(dl_rq); > > + if (dl_se->dl_new) > + add_average_bw(dl_se, dl_rq); > + > /* > * The arrival of a new instance needs special treatment, i.e., > * the actual scheduling parameters have to be "renewed". > @@ -741,8 +762,6 @@ static void update_curr_dl(struct rq *rq) > curr->se.exec_start = rq_clock_task(rq); > cpuacct_charge(curr, delta_exec); > > - sched_rt_avg_update(rq, delta_exec); > - > dl_se->runtime -= dl_se->dl_yielded ? 0 : delta_exec; > if (dl_runtime_exceeded(dl_se)) { > dl_se->dl_throttled = 1; > @@ -1241,6 +1260,8 @@ static void task_fork_dl(struct task_struct *p) > static void task_dead_dl(struct task_struct *p) > { > struct dl_bw *dl_b = dl_bw_of(task_cpu(p)); > + struct dl_rq *dl_rq = dl_rq_of_se(&p->dl); > + struct rq *rq = rq_of_dl_rq(dl_rq); > > /* > * Since we are TASK_DEAD we won't slip out of the domain! > @@ -1249,6 +1270,8 @@ static void task_dead_dl(struct task_struct *p) > /* XXX we should retain the bw until 0-lag */ > dl_b->total_bw -= p->dl.dl_bw; > raw_spin_unlock_irq(&dl_b->lock); > + > + clear_average_bw(&p->dl, &rq->dl); > } > > static void set_curr_task_dl(struct rq *rq) > @@ -1556,7 +1579,9 @@ retry: > } > > deactivate_task(rq, next_task, 0); > + clear_average_bw(&next_task->dl, &rq->dl); > set_task_cpu(next_task, later_rq->cpu); > + add_average_bw(&next_task->dl, &later_rq->dl); > activate_task(later_rq, next_task, 0); > ret = 1; > > @@ -1644,7 +1669,9 @@ static void pull_dl_task(struct rq *this_rq) > resched = true; > > deactivate_task(src_rq, p, 0); > + clear_average_bw(&p->dl, &src_rq->dl); > set_task_cpu(p, this_cpu); > + add_average_bw(&p->dl, &this_rq->dl); > activate_task(this_rq, p, 0); > dmin = p->dl.deadline; > > @@ -1750,6 +1777,8 @@ static void switched_from_dl(struct rq *rq, struct task_struct *p) > if (!start_dl_timer(p)) > __dl_clear_params(p); > > + clear_average_bw(&p->dl, &rq->dl); > + > /* > * Since this might be the only -deadline task on the rq, > * this is the right place to try to pull some other one > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 4c49f76..ce05f61 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -6203,6 +6203,14 @@ static unsigned long scale_rt_capacity(int cpu) > > used = div_u64(avg, total); > > + /* > + * deadline bandwidth is defined at system level so we must > + * weight this bandwidth with the max capacity of the system. > + * As a reminder, avg_bw is 20bits width and > + * scale_cpu_capacity is 10 bits width > + */ > + used += div_u64(rq->dl.avg_bw, arch_scale_cpu_capacity(NULL, cpu)); > + > if (likely(used < SCHED_CAPACITY_SCALE)) > return SCHED_CAPACITY_SCALE - used; > > diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h > index 08858d1..e44c6be 100644 > --- a/kernel/sched/sched.h > +++ b/kernel/sched/sched.h > @@ -519,6 +519,8 @@ struct dl_rq { > #else > struct dl_bw dl_bw; > #endif > + /* This is the "average utilization" for this runqueue */ > + s64 avg_bw; > }; > > #ifdef CONFIG_SMP > -- > 2.4.10 >
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