Commit 934fc331 authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

sched/cpupri: Remap CPUPRI_NORMAL to MAX_RT_PRIO-1 



This makes the mapping continuous and frees up 100 for other usage.

Prev mapping:

p->rt_priority   p->prio   newpri   cpupri

                               -1       -1 (CPUPRI_INVALID)

                              100        0 (CPUPRI_NORMAL)

             1        98       98        1
           ...
            49        50       50       49
            50        49       49       50
           ...
            99         0        0       99

New mapping:

p->rt_priority   p->prio   newpri   cpupri

                               -1       -1 (CPUPRI_INVALID)

                               99        0 (CPUPRI_NORMAL)

             1        98       98        1
           ...
            49        50       50       49
            50        49       49       50
           ...
            99         0        0       99

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarDietmar Eggemann <dietmar.eggemann@arm.com>
parent 1b08782c

kernel/sched/cpupri.c

+27 −7
Original line number Diff line number Diff line
@@ -24,17 +24,37 @@ 
 */

#include "sched.h"



/* Convert between a 140 based task->prio, and our 100 based cpupri */

/*

 * p->rt_priority   p->prio   newpri   cpupri

 *

 *				  -1       -1 (CPUPRI_INVALID)

 *

 *				  99        0 (CPUPRI_NORMAL)

 *

 *		1        98       98        1

 *	      ...

 *	       49        50       50       49

 *	       50        49       49       50

 *	      ...

 *	       99         0        0       99

 */

static int convert_prio(int prio)

{

	int cpupri;



	if (prio == CPUPRI_INVALID)

		cpupri = CPUPRI_INVALID;

	else if (prio >= MAX_RT_PRIO)

		cpupri = CPUPRI_NORMAL;

	else

		cpupri = MAX_RT_PRIO - prio - 1;

	switch (prio) {

	case CPUPRI_INVALID:

		cpupri = CPUPRI_INVALID;	/* -1 */

		break;



	case 0 ... 98:

		cpupri = MAX_RT_PRIO-1 - prio;	/* 1 ... 99 */

		break;



	case MAX_RT_PRIO-1:

		cpupri = CPUPRI_NORMAL;		/*  0 */

		break;

	}



	return cpupri;

}

kernel/sched/rt.c

+9 −7
Original line number Diff line number Diff line
@@ -89,8 +89,8 @@ void init_rt_rq(struct rt_rq *rt_rq) 
	__set_bit(MAX_RT_PRIO, array->bitmap);



#if defined CONFIG_SMP

	rt_rq->highest_prio.curr = MAX_RT_PRIO;

	rt_rq->highest_prio.next = MAX_RT_PRIO;

	rt_rq->highest_prio.curr = MAX_RT_PRIO-1;

	rt_rq->highest_prio.next = MAX_RT_PRIO-1;

	rt_rq->rt_nr_migratory = 0;

	rt_rq->overloaded = 0;

	plist_head_init(&rt_rq->pushable_tasks);
@@ -161,7 +161,7 @@ void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq, 
{

	struct rq *rq = cpu_rq(cpu);



	rt_rq->highest_prio.curr = MAX_RT_PRIO;

	rt_rq->highest_prio.curr = MAX_RT_PRIO-1;

	rt_rq->rt_nr_boosted = 0;

	rt_rq->rq = rq;

	rt_rq->tg = tg;
@@ -393,8 +393,9 @@ static void dequeue_pushable_task(struct rq *rq, struct task_struct *p) 
		p = plist_first_entry(&rq->rt.pushable_tasks,

				      struct task_struct, pushable_tasks);

		rq->rt.highest_prio.next = p->prio;

	} else

		rq->rt.highest_prio.next = MAX_RT_PRIO;

	} else {

		rq->rt.highest_prio.next = MAX_RT_PRIO-1;

	}

}



#else
@@ -1147,8 +1148,9 @@ dec_rt_prio(struct rt_rq *rt_rq, int prio) 
				sched_find_first_bit(array->bitmap);

		}



	} else

		rt_rq->highest_prio.curr = MAX_RT_PRIO;

	} else {

		rt_rq->highest_prio.curr = MAX_RT_PRIO-1;

	}



	dec_rt_prio_smp(rt_rq, prio, prev_prio);

}

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