[tip: sched/core] sched/cpupri: Remap CPUPRI_NORMAL to MAX_RT_PRIO-1
From: tip-bot2 for Peter Zijlstra
Date: Thu Oct 29 2020 - 06:52:29 EST
The following commit has been merged into the sched/core branch of tip:
Commit-ID: 934fc3314b39e16a89fc4d5d0d5cbfe71dcbe7b1
Gitweb: https://git.kernel.org/tip/934fc3314b39e16a89fc4d5d0d5cbfe71dcbe7b1
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Wed, 14 Oct 2020 21:06:49 +02:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Thu, 29 Oct 2020 11:00:30 +01:00
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: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
---
kernel/sched/cpupri.c | 34 +++++++++++++++++++++++++++-------
kernel/sched/rt.c | 16 +++++++++-------
2 files changed, 36 insertions(+), 14 deletions(-)
diff --git a/kernel/sched/cpupri.c b/kernel/sched/cpupri.c
index 8d9952a..e434910 100644
--- a/kernel/sched/cpupri.c
+++ b/kernel/sched/cpupri.c
@@ -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;
}
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 49ec096..8a3b1ba 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -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);
}