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sched/dl/Documentation: Split Section 3

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Introduce 4 subsections to make Section 3 more readable.

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/1431954032-16473-10-git-send-email-luca.abeni@unitn.it
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Luca Abeni 2015-05-18 15:00:32 +02:00 committed by Ingo Molnar
parent 7874085890
commit 6aaa10254d
1 changed files with 16 additions and 0 deletions
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16
Documentation/scheduler/sched-deadline.txt
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@ -8,6 +8,10 @@ CONTENTS
1. Overview
2. Scheduling algorithm
3. Scheduling Real-Time Tasks
3.1 Definitions
3.2 Schedulability Analysis for Uniprocessor Systems
3.3 Schedulability Analysis for Multiprocessor Systems
3.4 Relationship with SCHED_DEADLINE Parameters
4. Bandwidth management
4.1 System-wide settings
4.2 Task interface
@ -126,6 +130,9 @@ CONTENTS
suited for periodic or sporadic real-time tasks that need guarantees on their
timing behavior, e.g., multimedia, streaming, control applications, etc.
3.1 Definitions
------------------------
A typical real-time task is composed of a repetition of computation phases
(task instances, or jobs) which are activated on a periodic or sporadic
fashion.
@ -166,6 +173,9 @@ CONTENTS
is the minimum WCET, and U_max = max{WCET_i/P_i} is the maximum
utilization[12].
3.2 Schedulability Analysis for Uniprocessor Systems
------------------------
If M=1 (uniprocessor system), or in case of partitioned scheduling (each
real-time task is statically assigned to one and only one CPU), it is
possible to formally check if all the deadlines are respected.
@ -204,6 +214,9 @@ CONTENTS
time-consuming to be performed on-line. Hence, as explained in Section
4 Linux uses an admission test based on the tasks' utilizations.
3.3 Schedulability Analysis for Multiprocessor Systems
------------------------
On multiprocessor systems with global EDF scheduling (non partitioned
systems), a sufficient test for schedulability can not be based on the
utilizations or densities: it can be shown that even if D_i = P_i task
@ -249,6 +262,9 @@ CONTENTS
the total utilization is smaller or equal than M then the response times of
the tasks are limited.
3.4 Relationship with SCHED_DEADLINE Parameters
------------------------
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)