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Message-ID: <alpine.LFD.2.20.1708262154150.14288@knanqh.ubzr>
Date: Sat, 26 Aug 2017 21:56:07 -0400 (EDT)
From: Nicolas Pitre <nicolas.pitre@...aro.org>
To: Ingo Molnar <mingo@...nel.org>
cc: Ingo Molnar <mingo@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] sched/deadline: make it configurable
Ping.
On Thu, 17 Aug 2017, Nicolas Pitre wrote:
> Ping.
>
> On Thu, 3 Aug 2017, Nicolas Pitre wrote:
>
> > On most small systems, the deadline scheduler class is a luxury that
> > rarely gets used if at all. It is preferable to have the ability to
> > configure it out to reduce the kernel size in that case.
> >
> > Before:
> >
> > $ size -t kernel/sched/built-in.o
> > text data bss dec hex filename
> > [...]
> > 24435 3452 108 27995 6d5b (TOTALS)
> >
> > With CONFIG_SCHED_DL=n:
> >
> > $ size -t kernel/sched/built-in.o
> > text data bss dec hex filename
> > [...]
> > 18336 3388 92 21816 5538 (TOTALS)
> >
> > Signed-off-by: Nicolas Pitre <nico@...aro.org>
> > ---
> >
> > Changes from v1:
> >
> > - fix for a compilation error found by kbuild test robot
> >
> > include/linux/sched.h | 2 ++
> > include/linux/sched/deadline.h | 8 +++++++-
> > init/Kconfig | 8 ++++++++
> > kernel/locking/rtmutex.c | 6 +++---
> > kernel/sched/Makefile | 5 +++--
> > kernel/sched/core.c | 15 ++++++++------
> > kernel/sched/cpudeadline.h | 7 ++++++-
> > kernel/sched/debug.c | 4 ++++
> > kernel/sched/rt.c | 13 ++++++++-----
> > kernel/sched/sched.h | 44 ++++++++++++++++++++++++++++++++++--------
> > kernel/sched/stop_task.c | 4 ++++
> > 11 files changed, 90 insertions(+), 26 deletions(-)
> >
> > diff --git a/include/linux/sched.h b/include/linux/sched.h
> > index 8337e2db0b..5240f8c0d3 100644
> > --- a/include/linux/sched.h
> > +++ b/include/linux/sched.h
> > @@ -565,7 +565,9 @@ struct task_struct {
> > #ifdef CONFIG_CGROUP_SCHED
> > struct task_group *sched_task_group;
> > #endif
> > +#ifdef CONFIG_SCHED_DL
> > struct sched_dl_entity dl;
> > +#endif
> >
> > #ifdef CONFIG_PREEMPT_NOTIFIERS
> > /* List of struct preempt_notifier: */
> > diff --git a/include/linux/sched/deadline.h b/include/linux/sched/deadline.h
> > index 975be862e0..8f191a17dd 100644
> > --- a/include/linux/sched/deadline.h
> > +++ b/include/linux/sched/deadline.h
> > @@ -13,7 +13,7 @@
> >
> > static inline int dl_prio(int prio)
> > {
> > - if (unlikely(prio < MAX_DL_PRIO))
> > + if (IS_ENABLED(CONFIG_SCHED_DL) && unlikely(prio < MAX_DL_PRIO))
> > return 1;
> > return 0;
> > }
> > @@ -28,4 +28,10 @@ static inline bool dl_time_before(u64 a, u64 b)
> > return (s64)(a - b) < 0;
> > }
> >
> > +#ifdef CONFIG_SCHED_DL
> > +#define dl_deadline(tsk) (tsk)->dl.deadline
> > +#else
> > +#define dl_deadline(tsk) 0
> > +#endif
> > +
> > #endif /* _LINUX_SCHED_DEADLINE_H */
> > diff --git a/init/Kconfig b/init/Kconfig
> > index 5f0ef850e8..8a430de9f4 100644
> > --- a/init/Kconfig
> > +++ b/init/Kconfig
> > @@ -959,6 +959,14 @@ config SCHED_AUTOGROUP
> > desktop applications. Task group autogeneration is currently based
> > upon task session.
> >
> > +config SCHED_DL
> > + bool "Deadline Task Scheduling" if EXPERT
> > + default y
> > + help
> > + This adds the sched_dl scheduling class to the kernel providing
> > + support for the SCHED_DEADLINE policy. You might want to disable
> > + this to reduce the kernel size. If unsure say y.
> > +
> > config SYSFS_DEPRECATED
> > bool "Enable deprecated sysfs features to support old userspace tools"
> > depends on SYSFS
> > diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
> > index 649dc9d395..ebc7c3a610 100644
> > --- a/kernel/locking/rtmutex.c
> > +++ b/kernel/locking/rtmutex.c
> > @@ -228,7 +228,7 @@ static inline bool unlock_rt_mutex_safe(struct rt_mutex *lock,
> > * Only use with rt_mutex_waiter_{less,equal}()
> > */
> > #define task_to_waiter(p) \
> > - &(struct rt_mutex_waiter){ .prio = (p)->prio, .deadline = (p)->dl.deadline }
> > + &(struct rt_mutex_waiter){ .prio = (p)->prio, .deadline = dl_deadline(p) }
> >
> > static inline int
> > rt_mutex_waiter_less(struct rt_mutex_waiter *left,
> > @@ -692,7 +692,7 @@ static int rt_mutex_adjust_prio_chain(struct task_struct *task,
> > * the values of the node being removed.
> > */
> > waiter->prio = task->prio;
> > - waiter->deadline = task->dl.deadline;
> > + waiter->deadline = dl_deadline(task);
> >
> > rt_mutex_enqueue(lock, waiter);
> >
> > @@ -966,7 +966,7 @@ static int task_blocks_on_rt_mutex(struct rt_mutex *lock,
> > waiter->task = task;
> > waiter->lock = lock;
> > waiter->prio = task->prio;
> > - waiter->deadline = task->dl.deadline;
> > + waiter->deadline = dl_deadline(task);
> >
> > /* Get the top priority waiter on the lock */
> > if (rt_mutex_has_waiters(lock))
> > diff --git a/kernel/sched/Makefile b/kernel/sched/Makefile
> > index 53f0164ed3..6ba5664cfb 100644
> > --- a/kernel/sched/Makefile
> > +++ b/kernel/sched/Makefile
> > @@ -16,9 +16,10 @@ CFLAGS_core.o := $(PROFILING) -fno-omit-frame-pointer
> > endif
> >
> > obj-y += core.o loadavg.o clock.o cputime.o
> > -obj-y += idle_task.o fair.o rt.o deadline.o
> > +obj-y += idle_task.o fair.o rt.o
> > obj-y += wait.o wait_bit.o swait.o completion.o idle.o
> > -obj-$(CONFIG_SMP) += cpupri.o cpudeadline.o topology.o stop_task.o
> > +obj-$(CONFIG_SCHED_DL) += deadline.o $(if $(CONFIG_SMP),cpudeadline.o)
> > +obj-$(CONFIG_SMP) += cpupri.o topology.o stop_task.o
> > obj-$(CONFIG_SCHED_AUTOGROUP) += autogroup.o
> > obj-$(CONFIG_SCHEDSTATS) += stats.o
> > obj-$(CONFIG_SCHED_DEBUG) += debug.o
> > diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> > index 0869b20fba..2fc053f06a 100644
> > --- a/kernel/sched/core.c
> > +++ b/kernel/sched/core.c
> > @@ -636,7 +636,7 @@ bool sched_can_stop_tick(struct rq *rq)
> > int fifo_nr_running;
> >
> > /* Deadline tasks, even if single, need the tick */
> > - if (rq->dl.dl_nr_running)
> > + if (dl_nr_running(rq))
> > return false;
> >
> > /*
> > @@ -2166,10 +2166,12 @@ static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
> > memset(&p->se.statistics, 0, sizeof(p->se.statistics));
> > #endif
> >
> > +#ifdef CONFIG_SCHED_DL
> > RB_CLEAR_NODE(&p->dl.rb_node);
> > init_dl_task_timer(&p->dl);
> > init_dl_inactive_task_timer(&p->dl);
> > __dl_clear_params(p);
> > +#endif
> >
> > INIT_LIST_HEAD(&p->rt.run_list);
> > p->rt.timeout = 0;
> > @@ -3695,20 +3697,20 @@ void rt_mutex_setprio(struct task_struct *p, struct task_struct *pi_task)
> > if (dl_prio(prio)) {
> > if (!dl_prio(p->normal_prio) ||
> > (pi_task && dl_entity_preempt(&pi_task->dl, &p->dl))) {
> > - p->dl.dl_boosted = 1;
> > + dl_boosted(p) = 1;
> > queue_flag |= ENQUEUE_REPLENISH;
> > } else
> > - p->dl.dl_boosted = 0;
> > + dl_boosted(p) = 0;
> > p->sched_class = &dl_sched_class;
> > } else if (rt_prio(prio)) {
> > if (dl_prio(oldprio))
> > - p->dl.dl_boosted = 0;
> > + dl_boosted(p) = 0;
> > if (oldprio < prio)
> > queue_flag |= ENQUEUE_HEAD;
> > p->sched_class = &rt_sched_class;
> > } else {
> > if (dl_prio(oldprio))
> > - p->dl.dl_boosted = 0;
> > + dl_boosted(p) = 0;
> > if (rt_prio(oldprio))
> > p->rt.timeout = 0;
> > p->sched_class = &fair_sched_class;
> > @@ -5260,7 +5262,8 @@ int cpuset_cpumask_can_shrink(const struct cpumask *cur,
> > if (!cpumask_weight(cur))
> > return ret;
> >
> > - ret = dl_cpuset_cpumask_can_shrink(cur, trial);
> > + if (IS_ENABLED(CONFIG_SCHED_DL))
> > + ret = dl_cpuset_cpumask_can_shrink(cur, trial);
> >
> > return ret;
> > }
> > diff --git a/kernel/sched/cpudeadline.h b/kernel/sched/cpudeadline.h
> > index f7da8c55bb..5f4c10f837 100644
> > --- a/kernel/sched/cpudeadline.h
> > +++ b/kernel/sched/cpudeadline.h
> > @@ -25,10 +25,15 @@ int cpudl_find(struct cpudl *cp, struct task_struct *p,
> > struct cpumask *later_mask);
> > void cpudl_set(struct cpudl *cp, int cpu, u64 dl);
> > void cpudl_clear(struct cpudl *cp, int cpu);
> > -int cpudl_init(struct cpudl *cp);
> > void cpudl_set_freecpu(struct cpudl *cp, int cpu);
> > void cpudl_clear_freecpu(struct cpudl *cp, int cpu);
> > +#ifdef CONFIG_SCHED_DL
> > +int cpudl_init(struct cpudl *cp);
> > void cpudl_cleanup(struct cpudl *cp);
> > +#else
> > +#define cpudl_init(cp) 0
> > +#define cpudl_cleanup(cp) do { } while (0)
> > +#endif
> > #endif /* CONFIG_SMP */
> >
> > #endif /* _LINUX_CPUDL_H */
> > diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
> > index 4fa66de52b..f144d50da4 100644
> > --- a/kernel/sched/debug.c
> > +++ b/kernel/sched/debug.c
> > @@ -659,7 +659,9 @@ do { \
> > spin_lock_irqsave(&sched_debug_lock, flags);
> > print_cfs_stats(m, cpu);
> > print_rt_stats(m, cpu);
> > +#ifdef CONFIG_SCHED_DL
> > print_dl_stats(m, cpu);
> > +#endif
> >
> > print_rq(m, rq, cpu);
> > spin_unlock_irqrestore(&sched_debug_lock, flags);
> > @@ -967,10 +969,12 @@ void proc_sched_show_task(struct task_struct *p, struct seq_file *m)
> > #endif
> > P(policy);
> > P(prio);
> > +#ifdef CONFIG_SCHED_DL
> > if (p->policy == SCHED_DEADLINE) {
> > P(dl.runtime);
> > P(dl.deadline);
> > }
> > +#endif
> > #undef PN_SCHEDSTAT
> > #undef PN
> > #undef __PN
> > diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
> > index 45caf937ef..d48e75a4a8 100644
> > --- a/kernel/sched/rt.c
> > +++ b/kernel/sched/rt.c
> > @@ -1556,7 +1556,7 @@ pick_next_task_rt(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
> > * to re-start task selection.
> > */
> > if (unlikely((rq->stop && task_on_rq_queued(rq->stop)) ||
> > - rq->dl.dl_nr_running))
> > + dl_nr_running(rq)))
> > return RETRY_TASK;
> > }
> >
> > @@ -2716,16 +2716,19 @@ int sched_rt_handler(struct ctl_table *table, int write,
> > if (ret)
> > goto undo;
> >
> > - ret = sched_dl_global_validate();
> > - if (ret)
> > - goto undo;
> > + if (IS_ENABLED(CONFIG_SCHED_DL)) {
> > + ret = sched_dl_global_validate();
> > + if (ret)
> > + goto undo;
> > + }
> >
> > ret = sched_rt_global_constraints();
> > if (ret)
> > goto undo;
> >
> > sched_rt_do_global();
> > - sched_dl_do_global();
> > + if (IS_ENABLED(CONFIG_SCHED_DL))
> > + sched_dl_do_global();
> > }
> > if (0) {
> > undo:
> > diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> > index eeef1a3086..33a3391943 100644
> > --- a/kernel/sched/sched.h
> > +++ b/kernel/sched/sched.h
> > @@ -137,7 +137,7 @@ static inline int rt_policy(int policy)
> >
> > static inline int dl_policy(int policy)
> > {
> > - return policy == SCHED_DEADLINE;
> > + return IS_ENABLED(CONFIG_SCHED_DL) && policy == SCHED_DEADLINE;
> > }
> > static inline bool valid_policy(int policy)
> > {
> > @@ -158,11 +158,15 @@ static inline int task_has_dl_policy(struct task_struct *p)
> > /*
> > * Tells if entity @a should preempt entity @b.
> > */
> > +#ifdef CONFIG_SCHED_DL
> > static inline bool
> > dl_entity_preempt(struct sched_dl_entity *a, struct sched_dl_entity *b)
> > {
> > return dl_time_before(a->deadline, b->deadline);
> > }
> > +#else
> > +#define dl_entity_preempt(a, b) false
> > +#endif
> >
> > /*
> > * This is the priority-queue data structure of the RT scheduling class:
> > @@ -247,7 +251,6 @@ bool __dl_overflow(struct dl_bw *dl_b, int cpus, u64 old_bw, u64 new_bw)
> > }
> >
> > void dl_change_utilization(struct task_struct *p, u64 new_bw);
> > -extern void init_dl_bw(struct dl_bw *dl_b);
> > extern int sched_dl_global_validate(void);
> > extern void sched_dl_do_global(void);
> > extern int sched_dl_overflow(struct task_struct *p, int policy,
> > @@ -261,7 +264,27 @@ extern int dl_task_can_attach(struct task_struct *p,
> > const struct cpumask *cs_cpus_allowed);
> > extern int dl_cpuset_cpumask_can_shrink(const struct cpumask *cur,
> > const struct cpumask *trial);
> > +extern struct dl_bandwidth def_dl_bandwidth;
> > +
> > +struct dl_rq;
> > +
> > +#ifdef CONFIG_SCHED_DL
> > +#define dl_nr_running(rq) (rq)->dl.dl_nr_running
> > +#define dl_boosted(tsk) (tsk)->dl.dl_boosted
> > extern bool dl_cpu_busy(unsigned int cpu);
> > +extern void init_dl_bw(struct dl_bw *dl_b);
> > +extern void init_sched_dl_class(void);
> > +extern void init_dl_bandwidth(struct dl_bandwidth *dl_b, u64 period, u64 runtime);
> > +extern void init_dl_rq(struct dl_rq *dl_rq);
> > +#else
> > +#define dl_nr_running(rq) 0
> > +#define dl_boosted(tsk) (*(int *)0)
> > +#define dl_cpu_busy(cpu) false
> > +#define init_dl_bw(dl_b) do { } while (0)
> > +#define init_sched_dl_class() do { } while (0)
> > +#define init_dl_bandwidth(...) do { } while (0)
> > +#define init_dl_rq(dl_rq) do { } while (0)
> > +#endif
> >
> > #ifdef CONFIG_CGROUP_SCHED
> >
> > @@ -697,7 +720,9 @@ struct rq {
> >
> > struct cfs_rq cfs;
> > struct rt_rq rt;
> > +#ifdef CONFIG_SCHED_DL
> > struct dl_rq dl;
> > +#endif
> >
> > #ifdef CONFIG_FAIR_GROUP_SCHED
> > /* list of leaf cfs_rq on this cpu: */
> > @@ -1471,9 +1496,12 @@ static inline void set_curr_task(struct rq *rq, struct task_struct *curr)
> >
> > #ifdef CONFIG_SMP
> > #define sched_class_highest (&stop_sched_class)
> > -#else
> > +#elif defined(CONFIG_SCHED_DL)
> > #define sched_class_highest (&dl_sched_class)
> > +#else
> > +#define sched_class_highest (&rt_sched_class)
> > #endif
> > +
> > #define for_each_class(class) \
> > for (class = sched_class_highest; class; class = class->next)
> >
> > @@ -1524,7 +1552,6 @@ extern void sysrq_sched_debug_show(void);
> > extern void sched_init_granularity(void);
> > extern void update_max_interval(void);
> >
> > -extern void init_sched_dl_class(void);
> > extern void init_sched_rt_class(void);
> > extern void init_sched_fair_class(void);
> >
> > @@ -1534,8 +1561,6 @@ extern void resched_cpu(int cpu);
> > extern struct rt_bandwidth def_rt_bandwidth;
> > extern void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime);
> >
> > -extern struct dl_bandwidth def_dl_bandwidth;
> > -extern void init_dl_bandwidth(struct dl_bandwidth *dl_b, u64 period, u64 runtime);
> > extern void init_dl_task_timer(struct sched_dl_entity *dl_se);
> > extern void init_dl_inactive_task_timer(struct sched_dl_entity *dl_se);
> > extern void init_dl_rq_bw_ratio(struct dl_rq *dl_rq);
> > @@ -1966,7 +1991,6 @@ print_numa_stats(struct seq_file *m, int node, unsigned long tsf,
> >
> > extern void init_cfs_rq(struct cfs_rq *cfs_rq);
> > extern void init_rt_rq(struct rt_rq *rt_rq);
> > -extern void init_dl_rq(struct dl_rq *dl_rq);
> >
> > extern void cfs_bandwidth_usage_inc(void);
> > extern void cfs_bandwidth_usage_dec(void);
> > @@ -1985,7 +2009,11 @@ static inline void nohz_balance_exit_idle(unsigned int cpu) { }
> > #endif
> >
> >
> > -#ifdef CONFIG_SMP
> > +#if !defined(CONFIG_SCHED_DL)
> > +void __dl_update(struct dl_bw *dl_b, s64 bw)
> > +{
> > +}
> > +#elif defined(CONFIG_SMP)
> > static inline
> > void __dl_update(struct dl_bw *dl_b, s64 bw)
> > {
> > diff --git a/kernel/sched/stop_task.c b/kernel/sched/stop_task.c
> > index 9f69fb6308..5632dc3e63 100644
> > --- a/kernel/sched/stop_task.c
> > +++ b/kernel/sched/stop_task.c
> > @@ -110,7 +110,11 @@ static void update_curr_stop(struct rq *rq)
> > * Simple, special scheduling class for the per-CPU stop tasks:
> > */
> > const struct sched_class stop_sched_class = {
> > +#ifdef CONFIG_SCHED_DL
> > .next = &dl_sched_class,
> > +#else
> > + .next = &rt_sched_class,
> > +#endif
> >
> > .enqueue_task = enqueue_task_stop,
> > .dequeue_task = dequeue_task_stop,
> >
>
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