From: Luca Abeni <luca.abeni@unitn.it>
To: peterz@infradead.org
Cc: henrik@austad.us, juri.lelli@gmail.com, raistlin@linux.it,
mingo@kernel.org, linux-kernel@vger.kernel.org,
linux-doc@vger.kernel.org, Luca Abeni <luca.abeni@unitn.it>
Subject: [PATCH 9/9] Documentation/scheduler/sched-deadline.txt: Split Section 3
Date: Mon, 18 May 2015 15:00:32 +0200 [thread overview]
Message-ID: <1431954032-16473-10-git-send-email-luca.abeni@unitn.it> (raw)
In-Reply-To: <1431954032-16473-1-git-send-email-luca.abeni@unitn.it>
Introduce 4 subsections to make Section 3 more readable.
Signed-off-by: Luca Abeni <luca.abeni@unitn.it>
---
Documentation/scheduler/sched-deadline.txt | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/Documentation/scheduler/sched-deadline.txt b/Documentation/scheduler/sched-deadline.txt
index ead13bcc..163675c 100644
--- a/Documentation/scheduler/sched-deadline.txt
+++ b/Documentation/scheduler/sched-deadline.txt
@@ -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)
--
1.7.9.5
next prev parent reply other threads:[~2015-05-18 13:05 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-18 13:00 [PATCH 0/9] SCHED_DEADLINE documentation update Luca Abeni
2015-05-18 13:00 ` [PATCH 1/9] Documentation/scheduler/sched-deadline.txt: correct definition of density as C_i/min{D_i,P_i} Luca Abeni
2015-05-19 7:23 ` [tip:sched/core] sched/dl/Documentation: Correct the " tip-bot for Zhiqiang Zhang
2015-05-18 13:00 ` [PATCH 2/9] Documentation/scheduler/sched-deadline.txt: switch to American English Luca Abeni
2015-05-19 7:23 ` [tip:sched/core] sched/dl/Documentation: Switch " tip-bot for Luca Abeni
2015-05-18 13:00 ` [PATCH 3/9] Documentation/scheduler/sched-deadline.txt: fix typos Luca Abeni
2015-05-19 7:24 ` [tip:sched/core] sched/dl/Documentation: Fix typos tip-bot for Luca Abeni
2015-05-18 13:00 ` [PATCH 4/9] Documentation/scheduler/sched-deadline.txt: use consistent namings Luca Abeni
2015-05-19 7:24 ` [tip:sched/core] sched/dl/Documentation: Use consistent naming tip-bot for Luca Abeni
2015-05-18 13:00 ` [PATCH 5/9] Documentation/scheduler/sched-deadline.txt: remove _i from sum, max and min Luca Abeni
2015-05-19 7:24 ` [tip:sched/core] sched/dl/Documentation: Clarify indexing notation tip-bot for Luca Abeni
2015-05-18 13:00 ` [PATCH 6/9] Documentation/scheduler/sched-deadline.txt: Some notes on EDF schedulability Luca Abeni
2015-05-19 7:25 ` [tip:sched/core] sched/dl/Documentation: Add some " tip-bot for Luca Abeni
2015-05-18 13:00 ` [PATCH 7/9] Documentation/scheduler/sched-deadline.txt: add some references Luca Abeni
2015-05-19 7:25 ` [tip:sched/core] sched/dl/Documentation: Add " tip-bot for Luca Abeni
2015-05-18 13:00 ` [PATCH 8/9] Documentation/scheduler/sched-deadline.txt: relationship between tasks' deadlines and scheduling deadlines Luca Abeni
2015-05-19 7:25 ` [tip:sched/core] sched/dl/Documentation: Clarify the relationship between tasks' deadlines and absolute " tip-bot for Luca Abeni
2015-05-18 13:00 ` Luca Abeni [this message]
2015-05-19 7:26 ` [tip:sched/core] sched/dl/Documentation: Split Section 3 tip-bot for Luca Abeni
2015-05-19 13:26 ` [PATCH 0/9] SCHED_DEADLINE documentation update Henrik Austad
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