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Subject[tip:sched/core] sched/cpufreq: Change the worker kthread to SCHED_DEADLINE
Commit-ID:  794a56ebd9a57db12abaec63f038c6eb073461f7
Gitweb: https://git.kernel.org/tip/794a56ebd9a57db12abaec63f038c6eb073461f7
Author: Juri Lelli <juri.lelli@arm.com>
AuthorDate: Mon, 4 Dec 2017 11:23:20 +0100
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 10 Jan 2018 12:53:29 +0100

sched/cpufreq: Change the worker kthread to SCHED_DEADLINE

Worker kthread needs to be able to change frequency for all other
threads.

Make it special, just under STOP class.

Signed-off-by: Juri Lelli <juri.lelli@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Claudio Scordino <claudio@evidence.eu.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luca Abeni <luca.abeni@santannapisa.it>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: alessio.balsini@arm.com
Cc: bristot@redhat.com
Cc: dietmar.eggemann@arm.com
Cc: joelaf@google.com
Cc: juri.lelli@redhat.com
Cc: mathieu.poirier@linaro.org
Cc: morten.rasmussen@arm.com
Cc: patrick.bellasi@arm.com
Cc: rjw@rjwysocki.net
Cc: rostedt@goodmis.org
Cc: tkjos@android.com
Cc: tommaso.cucinotta@santannapisa.it
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/20171204102325.5110-4-juri.lelli@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
include/linux/sched.h | 1 +
kernel/sched/core.c | 13 ++++-
kernel/sched/cpufreq_schedutil.c | 19 ++++++--
kernel/sched/deadline.c | 103 +++++++++++++++++++++++++++------------
kernel/sched/sched.h | 30 +++++++++++-
5 files changed, 130 insertions(+), 36 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 274a449..f750671 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1431,6 +1431,7 @@ extern int idle_cpu(int cpu);
extern int sched_setscheduler(struct task_struct *, int, const struct sched_param *);
extern int sched_setscheduler_nocheck(struct task_struct *, int, const struct sched_param *);
extern int sched_setattr(struct task_struct *, const struct sched_attr *);
+extern int sched_setattr_nocheck(struct task_struct *, const struct sched_attr *);
extern struct task_struct *idle_task(int cpu);

/**
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index e28391b..402ef4f 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4085,7 +4085,7 @@ recheck:
return -EINVAL;
}

- if (attr->sched_flags & ~SCHED_FLAG_ALL)
+ if (attr->sched_flags & ~(SCHED_FLAG_ALL | SCHED_FLAG_SUGOV))
return -EINVAL;

/*
@@ -4152,6 +4152,9 @@ recheck:
}

if (user) {
+ if (attr->sched_flags & SCHED_FLAG_SUGOV)
+ return -EINVAL;
+
retval = security_task_setscheduler(p);
if (retval)
return retval;
@@ -4207,7 +4210,8 @@ change:
}
#endif
#ifdef CONFIG_SMP
- if (dl_bandwidth_enabled() && dl_policy(policy)) {
+ if (dl_bandwidth_enabled() && dl_policy(policy) &&
+ !(attr->sched_flags & SCHED_FLAG_SUGOV)) {
cpumask_t *span = rq->rd->span;

/*
@@ -4337,6 +4341,11 @@ int sched_setattr(struct task_struct *p, const struct sched_attr *attr)
}
EXPORT_SYMBOL_GPL(sched_setattr);

+int sched_setattr_nocheck(struct task_struct *p, const struct sched_attr *attr)
+{
+ return __sched_setscheduler(p, attr, false, true);
+}
+
/**
* sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
* @p: the task in question.
diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index 8d266bc..bd5f997 100644
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -474,7 +474,20 @@ static void sugov_policy_free(struct sugov_policy *sg_policy)
static int sugov_kthread_create(struct sugov_policy *sg_policy)
{
struct task_struct *thread;
- struct sched_param param = { .sched_priority = MAX_USER_RT_PRIO / 2 };
+ struct sched_attr attr = {
+ .size = sizeof(struct sched_attr),
+ .sched_policy = SCHED_DEADLINE,
+ .sched_flags = SCHED_FLAG_SUGOV,
+ .sched_nice = 0,
+ .sched_priority = 0,
+ /*
+ * Fake (unused) bandwidth; workaround to "fix"
+ * priority inheritance.
+ */
+ .sched_runtime = 1000000,
+ .sched_deadline = 10000000,
+ .sched_period = 10000000,
+ };
struct cpufreq_policy *policy = sg_policy->policy;
int ret;

@@ -492,10 +505,10 @@ static int sugov_kthread_create(struct sugov_policy *sg_policy)
return PTR_ERR(thread);
}

- ret = sched_setscheduler_nocheck(thread, SCHED_FIFO, &param);
+ ret = sched_setattr_nocheck(thread, &attr);
if (ret) {
kthread_stop(thread);
- pr_warn("%s: failed to set SCHED_FIFO\n", __func__);
+ pr_warn("%s: failed to set SCHED_DEADLINE\n", __func__);
return ret;
}

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index f584837..54a0dc1 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -78,7 +78,7 @@ static inline int dl_bw_cpus(int i)
#endif

static inline
-void add_running_bw(u64 dl_bw, struct dl_rq *dl_rq)
+void __add_running_bw(u64 dl_bw, struct dl_rq *dl_rq)
{
u64 old = dl_rq->running_bw;

@@ -91,7 +91,7 @@ void add_running_bw(u64 dl_bw, struct dl_rq *dl_rq)
}

static inline
-void sub_running_bw(u64 dl_bw, struct dl_rq *dl_rq)
+void __sub_running_bw(u64 dl_bw, struct dl_rq *dl_rq)
{
u64 old = dl_rq->running_bw;

@@ -105,7 +105,7 @@ void sub_running_bw(u64 dl_bw, struct dl_rq *dl_rq)
}

static inline
-void add_rq_bw(u64 dl_bw, struct dl_rq *dl_rq)
+void __add_rq_bw(u64 dl_bw, struct dl_rq *dl_rq)
{
u64 old = dl_rq->this_bw;

@@ -115,7 +115,7 @@ void add_rq_bw(u64 dl_bw, struct dl_rq *dl_rq)
}

static inline
-void sub_rq_bw(u64 dl_bw, struct dl_rq *dl_rq)
+void __sub_rq_bw(u64 dl_bw, struct dl_rq *dl_rq)
{
u64 old = dl_rq->this_bw;

@@ -127,16 +127,46 @@ void sub_rq_bw(u64 dl_bw, struct dl_rq *dl_rq)
SCHED_WARN_ON(dl_rq->running_bw > dl_rq->this_bw);
}

+static inline
+void add_rq_bw(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
+{
+ if (!dl_entity_is_special(dl_se))
+ __add_rq_bw(dl_se->dl_bw, dl_rq);
+}
+
+static inline
+void sub_rq_bw(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
+{
+ if (!dl_entity_is_special(dl_se))
+ __sub_rq_bw(dl_se->dl_bw, dl_rq);
+}
+
+static inline
+void add_running_bw(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
+{
+ if (!dl_entity_is_special(dl_se))
+ __add_running_bw(dl_se->dl_bw, dl_rq);
+}
+
+static inline
+void sub_running_bw(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
+{
+ if (!dl_entity_is_special(dl_se))
+ __sub_running_bw(dl_se->dl_bw, dl_rq);
+}
+
void dl_change_utilization(struct task_struct *p, u64 new_bw)
{
struct rq *rq;

+ BUG_ON(p->dl.flags & SCHED_FLAG_SUGOV);
+
if (task_on_rq_queued(p))
return;

rq = task_rq(p);
if (p->dl.dl_non_contending) {
- sub_running_bw(p->dl.dl_bw, &rq->dl);
+ sub_running_bw(&p->dl, &rq->dl);
p->dl.dl_non_contending = 0;
/*
* If the timer handler is currently running and the
@@ -148,8 +178,8 @@ void dl_change_utilization(struct task_struct *p, u64 new_bw)
if (hrtimer_try_to_cancel(&p->dl.inactive_timer) == 1)
put_task_struct(p);
}
- sub_rq_bw(p->dl.dl_bw, &rq->dl);
- add_rq_bw(new_bw, &rq->dl);
+ __sub_rq_bw(p->dl.dl_bw, &rq->dl);
+ __add_rq_bw(new_bw, &rq->dl);
}

/*
@@ -221,6 +251,9 @@ static void task_non_contending(struct task_struct *p)
if (dl_se->dl_runtime == 0)
return;

+ if (dl_entity_is_special(dl_se))
+ return;
+
WARN_ON(hrtimer_active(&dl_se->inactive_timer));
WARN_ON(dl_se->dl_non_contending);

@@ -240,12 +273,12 @@ static void task_non_contending(struct task_struct *p)
*/
if (zerolag_time < 0) {
if (dl_task(p))
- sub_running_bw(dl_se->dl_bw, dl_rq);
+ sub_running_bw(dl_se, dl_rq);
if (!dl_task(p) || p->state == TASK_DEAD) {
struct dl_bw *dl_b = dl_bw_of(task_cpu(p));

if (p->state == TASK_DEAD)
- sub_rq_bw(p->dl.dl_bw, &rq->dl);
+ sub_rq_bw(&p->dl, &rq->dl);
raw_spin_lock(&dl_b->lock);
__dl_sub(dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p)));
__dl_clear_params(p);
@@ -272,7 +305,7 @@ static void task_contending(struct sched_dl_entity *dl_se, int flags)
return;

if (flags & ENQUEUE_MIGRATED)
- add_rq_bw(dl_se->dl_bw, dl_rq);
+ add_rq_bw(dl_se, dl_rq);

if (dl_se->dl_non_contending) {
dl_se->dl_non_contending = 0;
@@ -293,7 +326,7 @@ static void task_contending(struct sched_dl_entity *dl_se, int flags)
* when the "inactive timer" fired).
* So, add it back.
*/
- add_running_bw(dl_se->dl_bw, dl_rq);
+ add_running_bw(dl_se, dl_rq);
}
}

@@ -1149,6 +1182,9 @@ static void update_curr_dl(struct rq *rq)

sched_rt_avg_update(rq, delta_exec);

+ if (dl_entity_is_special(dl_se))
+ return;
+
if (unlikely(dl_se->flags & SCHED_FLAG_RECLAIM))
delta_exec = grub_reclaim(delta_exec, rq, &curr->dl);
dl_se->runtime -= delta_exec;
@@ -1211,8 +1247,8 @@ static enum hrtimer_restart inactive_task_timer(struct hrtimer *timer)
struct dl_bw *dl_b = dl_bw_of(task_cpu(p));

if (p->state == TASK_DEAD && dl_se->dl_non_contending) {
- sub_running_bw(p->dl.dl_bw, dl_rq_of_se(&p->dl));
- sub_rq_bw(p->dl.dl_bw, dl_rq_of_se(&p->dl));
+ sub_running_bw(&p->dl, dl_rq_of_se(&p->dl));
+ sub_rq_bw(&p->dl, dl_rq_of_se(&p->dl));
dl_se->dl_non_contending = 0;
}

@@ -1229,7 +1265,7 @@ static enum hrtimer_restart inactive_task_timer(struct hrtimer *timer)
sched_clock_tick();
update_rq_clock(rq);

- sub_running_bw(dl_se->dl_bw, &rq->dl);
+ sub_running_bw(dl_se, &rq->dl);
dl_se->dl_non_contending = 0;
unlock:
task_rq_unlock(rq, p, &rf);
@@ -1423,8 +1459,8 @@ static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags)
dl_check_constrained_dl(&p->dl);

if (p->on_rq == TASK_ON_RQ_MIGRATING || flags & ENQUEUE_RESTORE) {
- add_rq_bw(p->dl.dl_bw, &rq->dl);
- add_running_bw(p->dl.dl_bw, &rq->dl);
+ add_rq_bw(&p->dl, &rq->dl);
+ add_running_bw(&p->dl, &rq->dl);
}

/*
@@ -1464,8 +1500,8 @@ static void dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags)
__dequeue_task_dl(rq, p, flags);

if (p->on_rq == TASK_ON_RQ_MIGRATING || flags & DEQUEUE_SAVE) {
- sub_running_bw(p->dl.dl_bw, &rq->dl);
- sub_rq_bw(p->dl.dl_bw, &rq->dl);
+ sub_running_bw(&p->dl, &rq->dl);
+ sub_rq_bw(&p->dl, &rq->dl);
}

/*
@@ -1571,7 +1607,7 @@ static void migrate_task_rq_dl(struct task_struct *p)
*/
raw_spin_lock(&rq->lock);
if (p->dl.dl_non_contending) {
- sub_running_bw(p->dl.dl_bw, &rq->dl);
+ sub_running_bw(&p->dl, &rq->dl);
p->dl.dl_non_contending = 0;
/*
* If the timer handler is currently running and the
@@ -1583,7 +1619,7 @@ static void migrate_task_rq_dl(struct task_struct *p)
if (hrtimer_try_to_cancel(&p->dl.inactive_timer) == 1)
put_task_struct(p);
}
- sub_rq_bw(p->dl.dl_bw, &rq->dl);
+ sub_rq_bw(&p->dl, &rq->dl);
raw_spin_unlock(&rq->lock);
}

@@ -2026,11 +2062,11 @@ retry:
}

deactivate_task(rq, next_task, 0);
- sub_running_bw(next_task->dl.dl_bw, &rq->dl);
- sub_rq_bw(next_task->dl.dl_bw, &rq->dl);
+ sub_running_bw(&next_task->dl, &rq->dl);
+ sub_rq_bw(&next_task->dl, &rq->dl);
set_task_cpu(next_task, later_rq->cpu);
- add_rq_bw(next_task->dl.dl_bw, &later_rq->dl);
- add_running_bw(next_task->dl.dl_bw, &later_rq->dl);
+ add_rq_bw(&next_task->dl, &later_rq->dl);
+ add_running_bw(&next_task->dl, &later_rq->dl);
activate_task(later_rq, next_task, 0);
ret = 1;

@@ -2118,11 +2154,11 @@ static void pull_dl_task(struct rq *this_rq)
resched = true;

deactivate_task(src_rq, p, 0);
- sub_running_bw(p->dl.dl_bw, &src_rq->dl);
- sub_rq_bw(p->dl.dl_bw, &src_rq->dl);
+ sub_running_bw(&p->dl, &src_rq->dl);
+ sub_rq_bw(&p->dl, &src_rq->dl);
set_task_cpu(p, this_cpu);
- add_rq_bw(p->dl.dl_bw, &this_rq->dl);
- add_running_bw(p->dl.dl_bw, &this_rq->dl);
+ add_rq_bw(&p->dl, &this_rq->dl);
+ add_running_bw(&p->dl, &this_rq->dl);
activate_task(this_rq, p, 0);
dmin = p->dl.deadline;

@@ -2231,7 +2267,7 @@ static void switched_from_dl(struct rq *rq, struct task_struct *p)
task_non_contending(p);

if (!task_on_rq_queued(p))
- sub_rq_bw(p->dl.dl_bw, &rq->dl);
+ sub_rq_bw(&p->dl, &rq->dl);

/*
* We cannot use inactive_task_timer() to invoke sub_running_bw()
@@ -2263,7 +2299,7 @@ static void switched_to_dl(struct rq *rq, struct task_struct *p)

/* If p is not queued we will update its parameters at next wakeup. */
if (!task_on_rq_queued(p)) {
- add_rq_bw(p->dl.dl_bw, &rq->dl);
+ add_rq_bw(&p->dl, &rq->dl);

return;
}
@@ -2442,6 +2478,9 @@ int sched_dl_overflow(struct task_struct *p, int policy,
u64 new_bw = dl_policy(policy) ? to_ratio(period, runtime) : 0;
int cpus, err = -1;

+ if (attr->sched_flags & SCHED_FLAG_SUGOV)
+ return 0;
+
/* !deadline task may carry old deadline bandwidth */
if (new_bw == p->dl.dl_bw && task_has_dl_policy(p))
return 0;
@@ -2528,6 +2567,10 @@ void __getparam_dl(struct task_struct *p, struct sched_attr *attr)
*/
bool __checkparam_dl(const struct sched_attr *attr)
{
+ /* special dl tasks don't actually use any parameter */
+ if (attr->sched_flags & SCHED_FLAG_SUGOV)
+ return true;
+
/* deadline != 0 */
if (attr->sched_deadline == 0)
return false;
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 863964f..c519733 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -157,12 +157,36 @@ static inline int task_has_dl_policy(struct task_struct *p)
}

/*
+ * !! For sched_setattr_nocheck() (kernel) only !!
+ *
+ * This is actually gross. :(
+ *
+ * It is used to make schedutil kworker(s) higher priority than SCHED_DEADLINE
+ * tasks, but still be able to sleep. We need this on platforms that cannot
+ * atomically change clock frequency. Remove once fast switching will be
+ * available on such platforms.
+ *
+ * SUGOV stands for SchedUtil GOVernor.
+ */
+#define SCHED_FLAG_SUGOV 0x10000000
+
+static inline bool dl_entity_is_special(struct sched_dl_entity *dl_se)
+{
+#ifdef CONFIG_CPU_FREQ_GOV_SCHEDUTIL
+ return unlikely(dl_se->flags & SCHED_FLAG_SUGOV);
+#else
+ return false;
+#endif
+}
+
+/*
* Tells if entity @a should preempt entity @b.
*/
static inline bool
dl_entity_preempt(struct sched_dl_entity *a, struct sched_dl_entity *b)
{
- return dl_time_before(a->deadline, b->deadline);
+ return dl_entity_is_special(a) ||
+ dl_time_before(a->deadline, b->deadline);
}

/*
@@ -2085,6 +2109,8 @@ static inline void cpufreq_update_util(struct rq *rq, unsigned int flags) {}
#define arch_scale_freq_invariant() (false)
#endif

+#ifdef CONFIG_CPU_FREQ_GOV_SCHEDUTIL
+
static inline unsigned long cpu_util_dl(struct rq *rq)
{
return (rq->dl.running_bw * SCHED_CAPACITY_SCALE) >> BW_SHIFT;
@@ -2094,3 +2120,5 @@ static inline unsigned long cpu_util_cfs(struct rq *rq)
{
return rq->cfs.avg.util_avg;
}
+
+#endif
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