diff options
| author | Tommaso Cucinotta <[email protected]> | 2016-09-09 19:45:17 +0200 |
|---|---|---|
| committer | Ingo Molnar <[email protected]> | 2016-09-10 11:17:41 +0200 |
| commit | b95202a3b6bb8715a716dbdb15cdb82bf622260b (patch) | |
| tree | 0c31a7148c829fd9f52e2ccbc89c03a25be48442 | |
| parent | de58af878d9146e5decc0cdd7acabaa82881cbe4 (diff) | |
sched/deadline: Document behavior of sched_yield()
This is a documentation only patch, explaining the
behavior of sched_yield() when a SCHED_DEADLINE
task calls it (give up remaining runtime and be
throttled until next period begins).
Signed-off-by: Tommaso Cucinotta <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Reviewed-by: Juri Lelli <[email protected]>
Reviewed-by: Luca Abeni <[email protected]>
Reviewed-by: Daniel Bristot de Oliveira <[email protected]>
Cc: Juri Lelli <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
| -rw-r--r-- | Documentation/scheduler/sched-deadline.txt | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/Documentation/scheduler/sched-deadline.txt b/Documentation/scheduler/sched-deadline.txt index 53a2fe1ae8b8..8e37b0ba2c9d 100644 --- a/Documentation/scheduler/sched-deadline.txt +++ b/Documentation/scheduler/sched-deadline.txt @@ -16,6 +16,7 @@ CONTENTS 4.1 System-wide settings 4.2 Task interface 4.3 Default behavior + 4.4 Behavior of sched_yield() 5. Tasks CPU affinity 5.1 SCHED_DEADLINE and cpusets HOWTO 6. Future plans @@ -426,6 +427,23 @@ CONTENTS Finally, notice that in order not to jeopardize the admission control a -deadline task cannot fork. + +4.4 Behavior of sched_yield() +----------------------------- + + When a SCHED_DEADLINE task calls sched_yield(), it gives up its + remaining runtime and is immediately throttled, until the next + period, when its runtime will be replenished (a special flag + dl_yielded is set and used to handle correctly throttling and runtime + replenishment after a call to sched_yield()). + + This behavior of sched_yield() allows the task to wake-up exactly at + the beginning of the next period. Also, this may be useful in the + future with bandwidth reclaiming mechanisms, where sched_yield() will + make the leftoever runtime available for reclamation by other + SCHED_DEADLINE tasks. + + 5. Tasks CPU affinity ===================== |