Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit f5832c19 authored by Nicolas Pitre's avatar Nicolas Pitre Committed by Ingo Molnar
Browse files

sched/core: Omit building stop_sched_class when !SMP 



The stop class is invoked through stop_machine only.
This is dead code on UP builds.

Signed-off-by: default avatarNicolas Pitre <nico@linaro.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170529210302.26868-3-nicolas.pitre@linaro.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 3effcb42

kernel/sched/Makefile

+2 −2
Original line number Diff line number Diff line
@@ -16,9 +16,9 @@ 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 stop_task.o

obj-y += idle_task.o fair.o rt.o deadline.o

obj-y += wait.o swait.o completion.o idle.o

obj-$(CONFIG_SMP) += cpupri.o cpudeadline.o topology.o

obj-$(CONFIG_SMP) += cpupri.o cpudeadline.o topology.o stop_task.o

obj-$(CONFIG_SCHED_AUTOGROUP) += autogroup.o

obj-$(CONFIG_SCHEDSTATS) += stats.o

obj-$(CONFIG_SCHED_DEBUG) += debug.o

kernel/sched/core.c

+30 −30
Original line number Diff line number Diff line
@@ -788,36 +788,6 @@ void deactivate_task(struct rq *rq, struct task_struct *p, int flags) 
	dequeue_task(rq, p, flags);

}



void sched_set_stop_task(int cpu, struct task_struct *stop)

{

	struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };

	struct task_struct *old_stop = cpu_rq(cpu)->stop;



	if (stop) {

		/*

		 * Make it appear like a SCHED_FIFO 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, &param);



		stop->sched_class = &stop_sched_class;

	}



	cpu_rq(cpu)->stop = stop;



	if (old_stop) {

		/*

		 * Reset it back to a normal scheduling class so that

		 * it can die in pieces.

		 */

		old_stop->sched_class = &rt_sched_class;

	}

}



/*

 * __normal_prio - return the priority that is based on the static prio

 */
@@ -1588,6 +1558,36 @@ static void update_avg(u64 *avg, u64 sample) 
	*avg += diff >> 3;

}



void sched_set_stop_task(int cpu, struct task_struct *stop)

{

	struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };

	struct task_struct *old_stop = cpu_rq(cpu)->stop;



	if (stop) {

		/*

		 * Make it appear like a SCHED_FIFO 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, &param);



		stop->sched_class = &stop_sched_class;

	}



	cpu_rq(cpu)->stop = stop;



	if (old_stop) {

		/*

		 * Reset it back to a normal scheduling class so that

		 * it can die in pieces.

		 */

		old_stop->sched_class = &rt_sched_class;

	}

}



#else



static inline int __set_cpus_allowed_ptr(struct task_struct *p,

kernel/sched/sched.h

+4 −0
Original line number Diff line number Diff line
@@ -1453,7 +1453,11 @@ static inline void set_curr_task(struct rq *rq, struct task_struct *curr) 
	curr->sched_class->set_curr_task(rq);

}



#ifdef CONFIG_SMP

#define sched_class_highest (&stop_sched_class)

#else

#define sched_class_highest (&dl_sched_class)

#endif

#define for_each_class(class) \

   for (class = sched_class_highest; class; class = class->next)