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authorHarald Gustafsson <harald.gustafsson@ericsson.com>2013-11-07 14:43:40 +0100
committerIngo Molnar <mingo@kernel.org>2014-01-13 13:41:09 +0100
commit755378a47192a3d1f7c3a8ca6c15c1cf76de0af2 (patch)
treeb5154fe4b499081b76958894bae2c6fa696c1925 /kernel
parent239be4a982154ea0c979fca5846349bb68973aed (diff)
downloadlinux-755378a47192a3d1f7c3a8ca6c15c1cf76de0af2.tar.bz2
sched/deadline: Add period support for SCHED_DEADLINE tasks
Make it possible to specify a period (different or equal than deadline) for -deadline tasks. Relative deadlines (D_i) are used on task arrivals to generate new scheduling (absolute) deadlines as "d = t + D_i", and periods (P_i) to postpone the scheduling deadlines as "d = d + P_i" when the budget is zero. This is in general useful to model (and schedule) tasks that have slow activation rates (long periods), but have to be scheduled soon once activated (short deadlines). Signed-off-by: Harald Gustafsson <harald.gustafsson@ericsson.com> Signed-off-by: Dario Faggioli <raistlin@linux.it> Signed-off-by: Juri Lelli <juri.lelli@gmail.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1383831828-15501-7-git-send-email-juri.lelli@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched/core.c10
-rw-r--r--kernel/sched/deadline.c10
2 files changed, 15 insertions, 5 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 548cc04aee45..069230b5c3fb 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1723,6 +1723,7 @@ static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
hrtimer_init(&p->dl.dl_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
p->dl.dl_runtime = p->dl.runtime = 0;
p->dl.dl_deadline = p->dl.deadline = 0;
+ p->dl.dl_period = 0;
p->dl.flags = 0;
INIT_LIST_HEAD(&p->rt.run_list);
@@ -3026,6 +3027,7 @@ __setparam_dl(struct task_struct *p, const struct sched_attr *attr)
init_dl_task_timer(dl_se);
dl_se->dl_runtime = attr->sched_runtime;
dl_se->dl_deadline = attr->sched_deadline;
+ dl_se->dl_period = attr->sched_period ?: dl_se->dl_deadline;
dl_se->flags = attr->sched_flags;
dl_se->dl_throttled = 0;
dl_se->dl_new = 1;
@@ -3067,19 +3069,23 @@ __getparam_dl(struct task_struct *p, struct sched_attr *attr)
attr->sched_priority = p->rt_priority;
attr->sched_runtime = dl_se->dl_runtime;
attr->sched_deadline = dl_se->dl_deadline;
+ attr->sched_period = dl_se->dl_period;
attr->sched_flags = dl_se->flags;
}
/*
* This function validates the new parameters of a -deadline task.
* We ask for the deadline not being zero, and greater or equal
- * than the runtime.
+ * than the runtime, as well as the period of being zero or
+ * greater than deadline.
*/
static bool
__checkparam_dl(const struct sched_attr *attr)
{
return attr && attr->sched_deadline != 0 &&
- (s64)(attr->sched_deadline - attr->sched_runtime) >= 0;
+ (attr->sched_period == 0 ||
+ (s64)(attr->sched_period - attr->sched_deadline) >= 0) &&
+ (s64)(attr->sched_deadline - attr->sched_runtime ) >= 0;
}
/*
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 21f58d261134..3958bc576d67 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -289,7 +289,7 @@ static void replenish_dl_entity(struct sched_dl_entity *dl_se)
* arbitrary large.
*/
while (dl_se->runtime <= 0) {
- dl_se->deadline += dl_se->dl_deadline;
+ dl_se->deadline += dl_se->dl_period;
dl_se->runtime += dl_se->dl_runtime;
}
@@ -329,9 +329,13 @@ static void replenish_dl_entity(struct sched_dl_entity *dl_se)
*
* This function returns true if:
*
- * runtime / (deadline - t) > dl_runtime / dl_deadline ,
+ * runtime / (deadline - t) > dl_runtime / dl_period ,
*
* IOW we can't recycle current parameters.
+ *
+ * Notice that the bandwidth check is done against the period. For
+ * task with deadline equal to period this is the same of using
+ * dl_deadline instead of dl_period in the equation above.
*/
static bool dl_entity_overflow(struct sched_dl_entity *dl_se, u64 t)
{
@@ -355,7 +359,7 @@ static bool dl_entity_overflow(struct sched_dl_entity *dl_se, u64 t)
* of anything below microseconds resolution is actually fiction
* (but still we want to give the user that illusion >;).
*/
- left = (dl_se->dl_deadline >> 10) * (dl_se->runtime >> 10);
+ left = (dl_se->dl_period >> 10) * (dl_se->runtime >> 10);
right = ((dl_se->deadline - t) >> 10) * (dl_se->dl_runtime >> 10);
return dl_time_before(right, left);