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Commit 34be3930 authored by Juri Lelli's avatar Juri Lelli Committed by Ingo Molnar
Browse files

sched/deadline: Implement "runtime overrun signal" support 

This patch adds the possibility of getting the delivery of a SIGXCPU
signal whenever there is a runtime overrun. The request is done through
the sched_flags field within the sched_attr structure.

Forward port of https://lkml.org/lkml/2009/10/16/170



Tested-by: default avatarMathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: default avatarJuri Lelli <juri.lelli@gmail.com>
Signed-off-by: default avatarClaudio Scordino <claudio@evidence.eu.com>
Signed-off-by: default avatarLuca Abeni <luca.abeni@santannapisa.it>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tommaso Cucinotta <tommaso.cucinotta@sssup.it>
Link: http://lkml.kernel.org/r/1513077024-25461-1-git-send-email-claudio@evidence.eu.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 7332dec0

include/linux/sched.h

+4 −0
Original line number Diff line number Diff line
@@ -472,11 +472,15 @@ struct sched_dl_entity { 
	 * has not been executed yet. This flag is useful to avoid race

	 * conditions between the inactive timer handler and the wakeup

	 * code.

	 *

	 * @dl_overrun tells if the task asked to be informed about runtime

	 * overruns.

	 */

	unsigned int			dl_throttled      : 1;

	unsigned int			dl_boosted        : 1;

	unsigned int			dl_yielded        : 1;

	unsigned int			dl_non_contending : 1;

	unsigned int			dl_overrun	  : 1;



	/*

	 * Bandwidth enforcement timer. Each -deadline task has its

include/uapi/linux/sched.h

+5 −0
Original line number Diff line number Diff line
@@ -49,5 +49,10 @@ 
 */

#define SCHED_FLAG_RESET_ON_FORK	0x01

#define SCHED_FLAG_RECLAIM		0x02

#define SCHED_FLAG_DL_OVERRUN		0x04



#define SCHED_FLAG_ALL	(SCHED_FLAG_RESET_ON_FORK	| \

			 SCHED_FLAG_RECLAIM		| \

			 SCHED_FLAG_DL_OVERRUN)



#endif /* _UAPI_LINUX_SCHED_H */

kernel/sched/core.c

+1 −2
Original line number Diff line number Diff line
@@ -4085,8 +4085,7 @@ static int __sched_setscheduler(struct task_struct *p, 
			return -EINVAL;

	}



	if (attr->sched_flags &

		~(SCHED_FLAG_RESET_ON_FORK | SCHED_FLAG_RECLAIM))

	if (attr->sched_flags & ~SCHED_FLAG_ALL)

		return -EINVAL;



	/*

kernel/sched/deadline.c

+7 −0
Original line number Diff line number Diff line
@@ -1155,6 +1155,12 @@ static void update_curr_dl(struct rq *rq) 
throttle:

	if (dl_runtime_exceeded(dl_se) || dl_se->dl_yielded) {

		dl_se->dl_throttled = 1;



		/* If requested, inform the user about runtime overruns. */

		if (dl_runtime_exceeded(dl_se) &&

		    (dl_se->flags & SCHED_FLAG_DL_OVERRUN))

			dl_se->dl_overrun = 1;



		__dequeue_task_dl(rq, curr, 0);

		if (unlikely(dl_se->dl_boosted || !start_dl_timer(curr)))

			enqueue_task_dl(rq, curr, ENQUEUE_REPLENISH);
@@ -2566,6 +2572,7 @@ void __dl_clear_params(struct task_struct *p) 
	dl_se->dl_throttled = 0;

	dl_se->dl_yielded = 0;

	dl_se->dl_non_contending = 0;

	dl_se->dl_overrun = 0;

}



bool dl_param_changed(struct task_struct *p, const struct sched_attr *attr)

kernel/time/posix-cpu-timers.c

+18 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <linux/tick.h>

#include <linux/workqueue.h>

#include <linux/compat.h>

#include <linux/sched/deadline.h>



#include "posix-timers.h"
@@ -791,6 +792,14 @@ check_timers_list(struct list_head *timers, 
	return 0;

}



static inline void check_dl_overrun(struct task_struct *tsk)

{

	if (tsk->dl.dl_overrun) {

		tsk->dl.dl_overrun = 0;

		__group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);

	}

}



/*

 * Check for any per-thread CPU timers that have fired and move them off

 * the tsk->cpu_timers[N] list onto the firing list.  Here we update the
@@ -804,6 +813,9 @@ static void check_thread_timers(struct task_struct *tsk, 
	u64 expires;

	unsigned long soft;



	if (dl_task(tsk))

		check_dl_overrun(tsk);



	/*

	 * If cputime_expires is zero, then there are no active

	 * per thread CPU timers.
@@ -906,6 +918,9 @@ static void check_process_timers(struct task_struct *tsk, 
	struct task_cputime cputime;

	unsigned long soft;



	if (dl_task(tsk))

		check_dl_overrun(tsk);



	/*

	 * If cputimer is not running, then there are no active

	 * process wide timers (POSIX 1.b, itimers, RLIMIT_CPU).
@@ -1111,6 +1126,9 @@ static inline int fastpath_timer_check(struct task_struct *tsk) 
			return 1;

	}



	if (dl_task(tsk) && tsk->dl.dl_overrun)

		return 1;



	return 0;

}