[PATCH] sched: add new SCHED_BATCH policy
Add a new SCHED_BATCH (3) scheduling policy: such tasks are presumed
CPU-intensive, and will acquire a constant +5 priority level penalty. Such
policy is nice for workloads that are non-interactive, but which do not
want to give up their nice levels. The policy is also useful for workloads
that want a deterministic scheduling policy without interactivity causing
extra preemptions (between that workload's tasks).
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/kernel/sched.c b/kernel/sched.c
index c9dec2a..e1dc903 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -748,10 +748,14 @@
unsigned long long __sleep_time = now - p->timestamp;
unsigned long sleep_time;
- if (__sleep_time > NS_MAX_SLEEP_AVG)
- sleep_time = NS_MAX_SLEEP_AVG;
- else
- sleep_time = (unsigned long)__sleep_time;
+ if (unlikely(p->policy == SCHED_BATCH))
+ sleep_time = 0;
+ else {
+ if (__sleep_time > NS_MAX_SLEEP_AVG)
+ sleep_time = NS_MAX_SLEEP_AVG;
+ else
+ sleep_time = (unsigned long)__sleep_time;
+ }
if (likely(sleep_time > 0)) {
/*
@@ -3560,7 +3564,7 @@
* The RT priorities are set via sched_setscheduler(), but we still
* allow the 'normal' nice value to be set - but as expected
* it wont have any effect on scheduling until the task is
- * not SCHED_NORMAL:
+ * not SCHED_NORMAL/SCHED_BATCH:
*/
if (rt_task(p)) {
p->static_prio = NICE_TO_PRIO(nice);
@@ -3706,10 +3710,16 @@
BUG_ON(p->array);
p->policy = policy;
p->rt_priority = prio;
- if (policy != SCHED_NORMAL)
+ if (policy != SCHED_NORMAL && policy != SCHED_BATCH) {
p->prio = MAX_RT_PRIO-1 - p->rt_priority;
- else
+ } else {
p->prio = p->static_prio;
+ /*
+ * SCHED_BATCH tasks are treated as perpetual CPU hogs:
+ */
+ if (policy == SCHED_BATCH)
+ p->sleep_avg = 0;
+ }
}
/**
@@ -3733,29 +3743,35 @@
if (policy < 0)
policy = oldpolicy = p->policy;
else if (policy != SCHED_FIFO && policy != SCHED_RR &&
- policy != SCHED_NORMAL)
- return -EINVAL;
+ policy != SCHED_NORMAL && policy != SCHED_BATCH)
+ return -EINVAL;
/*
* Valid priorities for SCHED_FIFO and SCHED_RR are
- * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL is 0.
+ * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL and
+ * SCHED_BATCH is 0.
*/
if (param->sched_priority < 0 ||
(p->mm && param->sched_priority > MAX_USER_RT_PRIO-1) ||
(!p->mm && param->sched_priority > MAX_RT_PRIO-1))
return -EINVAL;
- if ((policy == SCHED_NORMAL) != (param->sched_priority == 0))
+ if ((policy == SCHED_NORMAL || policy == SCHED_BATCH)
+ != (param->sched_priority == 0))
return -EINVAL;
/*
* Allow unprivileged RT tasks to decrease priority:
*/
if (!capable(CAP_SYS_NICE)) {
- /* can't change policy */
- if (policy != p->policy &&
- !p->signal->rlim[RLIMIT_RTPRIO].rlim_cur)
+ /*
+ * can't change policy, except between SCHED_NORMAL
+ * and SCHED_BATCH:
+ */
+ if (((policy != SCHED_NORMAL && p->policy != SCHED_BATCH) &&
+ (policy != SCHED_BATCH && p->policy != SCHED_NORMAL)) &&
+ !p->signal->rlim[RLIMIT_RTPRIO].rlim_cur)
return -EPERM;
/* can't increase priority */
- if (policy != SCHED_NORMAL &&
+ if ((policy != SCHED_NORMAL && policy != SCHED_BATCH) &&
param->sched_priority > p->rt_priority &&
param->sched_priority >
p->signal->rlim[RLIMIT_RTPRIO].rlim_cur)
@@ -4233,6 +4249,7 @@
ret = MAX_USER_RT_PRIO-1;
break;
case SCHED_NORMAL:
+ case SCHED_BATCH:
ret = 0;
break;
}
@@ -4256,6 +4273,7 @@
ret = 1;
break;
case SCHED_NORMAL:
+ case SCHED_BATCH:
ret = 0;
}
return ret;
