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authorLuca Abeni <luca.abeni@unitn.it>2015-05-18 15:00:31 +0200
committerIngo Molnar <mingo@kernel.org>2015-05-19 08:39:21 +0200
commit78740858903460d4b926b9a90c705fcb6103da54 (patch)
treea61741eb681a2f52a9d91c1072f2f03288a79b3d /Documentation
parent134136c4b730c1a4830a8b74e2717d858291361b (diff)
downloadlinux-78740858903460d4b926b9a90c705fcb6103da54.tar.bz2
sched/dl/Documentation: Clarify the relationship between tasks' deadlines and absolute scheduling deadlines
Clarify what is the relationship between tasks' parameters and scheduling parameters, explaining how to set the scheduling parameters so that all the absolute deadlines of a task are respected. Signed-off-by: Luca Abeni <luca.abeni@unitn.it> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: henrik@austad.us Cc: juri.lelli@gmail.com Cc: raistlin@linux.it Link: http://lkml.kernel.org/r/1431954032-16473-9-git-send-email-luca.abeni@unitn.it Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/scheduler/sched-deadline.txt14
1 files changed, 11 insertions, 3 deletions
diff --git a/Documentation/scheduler/sched-deadline.txt b/Documentation/scheduler/sched-deadline.txt
index 984a01d3c68f..2a924e19912a 100644
--- a/Documentation/scheduler/sched-deadline.txt
+++ b/Documentation/scheduler/sched-deadline.txt
@@ -249,9 +249,17 @@ CONTENTS
the total utilization is smaller or equal than M then the response times of
the tasks are limited.
- SCHED_DEADLINE can be used to schedule real-time tasks guaranteeing that
- the jobs' deadlines of a task are respected. In order to do this, a task
- must be scheduled by setting:
+ Finally, it is important to understand the relationship between the
+ SCHED_DEADLINE scheduling parameters described in Section 2 (runtime,
+ deadline and period) and the real-time task parameters (WCET, D, P)
+ described in this section. Note that the tasks' temporal constraints are
+ represented by its absolute deadlines d_j = r_j + D described above, while
+ SCHED_DEADLINE schedules the tasks according to scheduling deadlines (see
+ Section 2).
+ If an admission test is used to guarantee that the scheduling deadlines
+ are respected, then SCHED_DEADLINE can be used to schedule real-time tasks
+ guaranteeing that all the jobs' deadlines of a task are respected.
+ In order to do this, a task must be scheduled by setting:
- runtime >= WCET
- deadline = D