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| author | Tommaso Cucinotta <tommaso.cucinotta@sssup.it> | 2016-09-09 19:45:17 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-09-10 11:17:41 +0200 |
| commit | b95202a3b6bb8715a716dbdb15cdb82bf622260b (patch) | |
| tree | 0c31a7148c829fd9f52e2ccbc89c03a25be48442 | |
| parent | de58af878d9146e5decc0cdd7acabaa82881cbe4 (diff) | |
| download | linux-b95202a3b6bb8715a716dbdb15cdb82bf622260b.tar.gz linux-b95202a3b6bb8715a716dbdb15cdb82bf622260b.tar.bz2 linux-b95202a3b6bb8715a716dbdb15cdb82bf622260b.zip | |
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 <tommaso.cucinotta@sssup.it>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@arm.com>
Reviewed-by: Luca Abeni <luca.abeni@unitn.it>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Juri Lelli <juri.lelli@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-dl@retis.sssup.it
Link: http://lkml.kernel.org/r/1473443117-11794-2-git-send-email-tommaso.cucinotta@sssup.it
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -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 ===================== |