Adds support for compiling out the real-time scheduler (SCHED_FIFO and SCHED_RR) to save space. Changes sched_set_stop_task to use SCHED_NORMAL rather than SCHED_FIFO, since the kernel only uses this function as a fake scheduling priority for userspace to read to avoid exposing the stop class to userspace. Bloat-o-meter gives a space savings of 1877 bytes with REALTIME_SCHED turned off.
Userspace works fine with REALTIME_SCHED turned off. Processes attempting to set a real-time scheduling policy get EINVAL, exactly the response that the sched_setscheduler manpage documents you will get if the "scheduling policy is not one of the recognized policies." Signed-off-by: Trevor Brandt <[email protected]> Reviewed-by: Josh Triplett <[email protected]> --- v2: The second revision compiles out cpupri.c when REALTIME_SCHED=n. init/Kconfig | 8 ++++++++ kernel/sched/Makefile | 6 ++++-- kernel/sched/core.c | 14 ++++++-------- kernel/sched/cpupri.h | 3 ++- kernel/sched/rt.c | 2 -- kernel/sched/sched.h | 46 ++++++++++++++++++++++++++++++++++++++++++++++ kernel/sched/stop_task.c | 4 ++++ 7 files changed, 70 insertions(+), 13 deletions(-) diff --git a/init/Kconfig b/init/Kconfig index 3f42cd6..1206961 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -753,6 +753,7 @@ config CFS_BANDWIDTH config RT_GROUP_SCHED bool "Group scheduling for SCHED_RR/FIFO" + depends on REALTIME_SCHED depends on EXPERIMENTAL depends on CGROUP_SCHED default n @@ -972,6 +973,13 @@ menuconfig EXPERT environments which can tolerate a "non-standard" kernel. Only use this if you really know what you are doing. +config REALTIME_SCHED + bool "Realtime Scheduler" if EXPERT + default y + help + This option enables support for the realtime scheduler and the + corresponding scheduling classes SCHED_FIFO and SCHED_RR. + config UID16 bool "Enable 16-bit UID system calls" if EXPERT depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION) diff --git a/kernel/sched/Makefile b/kernel/sched/Makefile index 9a7dd35..76fe500 100644 --- a/kernel/sched/Makefile +++ b/kernel/sched/Makefile @@ -11,8 +11,10 @@ ifneq ($(CONFIG_SCHED_OMIT_FRAME_POINTER),y) CFLAGS_core.o := $(PROFILING) -fno-omit-frame-pointer endif -obj-y += core.o clock.o idle_task.o fair.o rt.o stop_task.o -obj-$(CONFIG_SMP) += cpupri.o +obj-y += core.o clock.o idle_task.o fair.o stop_task.o +obj-$(CONFIG_REALTIME_SCHED) += realtime.o +realtime-y += rt.o +realtime-$(CONFIG_SMP) += cpupri.o obj-$(CONFIG_SCHED_AUTOGROUP) += auto_group.o obj-$(CONFIG_SCHEDSTATS) += stats.o obj-$(CONFIG_SCHED_DEBUG) += debug.o diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 478a04c..3579286 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -85,6 +85,8 @@ #define CREATE_TRACE_POINTS #include <trace/events/sched.h> +struct rt_bandwidth def_rt_bandwidth; + void start_bandwidth_timer(struct hrtimer *period_timer, ktime_t period) { unsigned long delta; @@ -959,19 +961,15 @@ static int irqtime_account_si_update(void) void sched_set_stop_task(int cpu, struct task_struct *stop) { - struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 }; + struct sched_param param = { .sched_priority = 0 }; struct task_struct *old_stop = cpu_rq(cpu)->stop; if (stop) { /* - * Make it appear like a SCHED_FIFO task, its something + * Make it appear like a SCHED_NORMAL task, its something * userspace knows about and won't get confused about. - * - * Also, it will make PI more or less work without too - * much confusion -- but then, stop work should not - * rely on PI working anyway. */ - sched_setscheduler_nocheck(stop, SCHED_FIFO, ¶m); + sched_setscheduler_nocheck(stop, SCHED_NORMAL, ¶m); stop->sched_class = &stop_sched_class; } @@ -983,7 +981,7 @@ void sched_set_stop_task(int cpu, struct task_struct *stop) * Reset it back to a normal scheduling class so that * it can die in pieces. */ - old_stop->sched_class = &rt_sched_class; + old_stop->sched_class = &fair_sched_class; } } diff --git a/kernel/sched/cpupri.h b/kernel/sched/cpupri.h index fd7914c..8ee2796 100644 --- a/kernel/sched/cpupri.h +++ b/kernel/sched/cpupri.h @@ -20,7 +20,7 @@ struct cpupri { int cpu_to_pri[NR_CPUS]; }; -#ifdef CONFIG_SMP +#if defined(CONFIG_SMP) && defined(CONFIG_REALTIME_SCHED) int cpupri_find(struct cpupri *cp, struct task_struct *p, struct cpumask *lowest_mask); void cpupri_set(struct cpupri *cp, int cpu, int pri); @@ -32,6 +32,7 @@ static inline int cpupri_init(struct cpupri *cp) { return 0; } +static inline void cpupri_cleanup(struct cpupri *cp) { } #endif #endif /* _LINUX_CPUPRI_H */ diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index f42ae7f..4100803 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -9,8 +9,6 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun); -struct rt_bandwidth def_rt_bandwidth; - static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer) { struct rt_bandwidth *rt_b = diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 98c0c26..ed41cb7 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -47,6 +47,8 @@ extern __read_mostly int scheduler_running; */ #define RUNTIME_INF ((u64)~0ULL) +#ifdef CONFIG_REALTIME_SCHED + static inline int rt_policy(int policy) { if (policy == SCHED_FIFO || policy == SCHED_RR) @@ -59,6 +61,19 @@ static inline int task_has_rt_policy(struct task_struct *p) return rt_policy(p->policy); } +#else /* CONFIG_REALTIME_SCHED */ + +static inline int rt_policy(int policy) +{ + return 0; +} +static inline int task_has_rt_policy(struct task_struct *p) +{ + return 0; +} + +#endif /* CONFIG_REALTIME_SCHED */ + /* * This is the priority-queue data structure of the RT scheduling class: */ @@ -190,8 +205,17 @@ extern void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b); extern void __start_cfs_bandwidth(struct cfs_bandwidth *cfs_b); extern void unthrottle_cfs_rq(struct cfs_rq *cfs_rq); +#ifdef CONFIG_REALTIME_SCHED extern void free_rt_sched_group(struct task_group *tg); extern int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent); +#else +static inline void free_rt_sched_group(struct task_group *tg) { } +static inline int alloc_rt_sched_group(struct task_group *tg, + struct task_group *parent) +{ + return 1; +} +#endif extern void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq, struct sched_rt_entity *rt_se, int cpu, struct sched_rt_entity *parent); @@ -852,7 +876,11 @@ enum cpuacct_stat_index { for (class = sched_class_highest; class; class = class->next) extern const struct sched_class stop_sched_class; +#ifdef CONFIG_REALTIME_SCHED extern const struct sched_class rt_sched_class; +#else +static const struct sched_class rt_sched_class = { }; +#endif extern const struct sched_class fair_sched_class; extern const struct sched_class idle_sched_class; @@ -874,15 +902,29 @@ extern void sysrq_sched_debug_show(void); extern void sched_init_granularity(void); extern void update_max_interval(void); extern void update_group_power(struct sched_domain *sd, int cpu); +#ifdef CONFIG_REALTIME_SCHED extern int update_runtime(struct notifier_block *nfb, unsigned long action, void *hcpu); extern void init_sched_rt_class(void); +#else +static inline int update_runtime(struct notifier_block *nfb, + unsigned long action, void *hcpu) +{ + return 0; +} +static inline void init_sched_rt_class(void) { } +#endif extern void init_sched_fair_class(void); extern void resched_task(struct task_struct *p); extern void resched_cpu(int cpu); extern struct rt_bandwidth def_rt_bandwidth; +#ifdef CONFIG_REALTIME_SCHED extern void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime); +#else +static inline void init_rt_bandwidth(struct rt_bandwidth *rt_b, + u64 period, u64 runtime) { } +#endif extern void update_cpu_load(struct rq *this_rq); @@ -1150,7 +1192,11 @@ extern void print_cfs_stats(struct seq_file *m, int cpu); extern void print_rt_stats(struct seq_file *m, int cpu); extern void init_cfs_rq(struct cfs_rq *cfs_rq); +#ifdef CONFIG_REALTIME_SCHED extern void init_rt_rq(struct rt_rq *rt_rq, struct rq *rq); +#else +static inline void init_rt_rq(struct rt_rq *rt_rq, struct rq *rq) { } +#endif extern void unthrottle_offline_cfs_rqs(struct rq *rq); extern void account_cfs_bandwidth_used(int enabled, int was_enabled); diff --git a/kernel/sched/stop_task.c b/kernel/sched/stop_task.c index 7b386e8..5c29766 100644 --- a/kernel/sched/stop_task.c +++ b/kernel/sched/stop_task.c @@ -83,7 +83,11 @@ get_rr_interval_stop(struct rq *rq, struct task_struct *task) * Simple, special scheduling class for the per-CPU stop tasks: */ const struct sched_class stop_sched_class = { +#ifdef CONFIG_REALTIME_SCHED .next = &rt_sched_class, +#else + .next = &fair_sched_class, +#endif .enqueue_task = enqueue_task_stop, .dequeue_task = dequeue_task_stop, -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
