diff options
author | Luca Abeni <luca.abeni@unitn.it> | 2015-05-18 09:00:32 -0400 |
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committer | Ingo Molnar <mingo@kernel.org> | 2015-05-19 02:39:21 -0400 |
commit | 6aaa10254dfe61c8c5e87c26e21be0664782a5b4 (patch) | |
tree | 3a93ef074b6da8977ace24c00dd7533a979d3c6b /Documentation/scheduler | |
parent | 78740858903460d4b926b9a90c705fcb6103da54 (diff) |
sched/dl/Documentation: Split Section 3
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>
Diffstat (limited to 'Documentation/scheduler')
-rw-r--r-- | Documentation/scheduler/sched-deadline.txt | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/Documentation/scheduler/sched-deadline.txt b/Documentation/scheduler/sched-deadline.txt index 2a924e19912a..e114513a2731 100644 --- a/Documentation/scheduler/sched-deadline.txt +++ b/Documentation/scheduler/sched-deadline.txt | |||
@@ -8,6 +8,10 @@ CONTENTS | |||
8 | 1. Overview | 8 | 1. Overview |
9 | 2. Scheduling algorithm | 9 | 2. Scheduling algorithm |
10 | 3. Scheduling Real-Time Tasks | 10 | 3. Scheduling Real-Time Tasks |
11 | 3.1 Definitions | ||
12 | 3.2 Schedulability Analysis for Uniprocessor Systems | ||
13 | 3.3 Schedulability Analysis for Multiprocessor Systems | ||
14 | 3.4 Relationship with SCHED_DEADLINE Parameters | ||
11 | 4. Bandwidth management | 15 | 4. Bandwidth management |
12 | 4.1 System-wide settings | 16 | 4.1 System-wide settings |
13 | 4.2 Task interface | 17 | 4.2 Task interface |
@@ -126,6 +130,9 @@ CONTENTS | |||
126 | suited for periodic or sporadic real-time tasks that need guarantees on their | 130 | suited for periodic or sporadic real-time tasks that need guarantees on their |
127 | timing behavior, e.g., multimedia, streaming, control applications, etc. | 131 | timing behavior, e.g., multimedia, streaming, control applications, etc. |
128 | 132 | ||
133 | 3.1 Definitions | ||
134 | ------------------------ | ||
135 | |||
129 | A typical real-time task is composed of a repetition of computation phases | 136 | A typical real-time task is composed of a repetition of computation phases |
130 | (task instances, or jobs) which are activated on a periodic or sporadic | 137 | (task instances, or jobs) which are activated on a periodic or sporadic |
131 | fashion. | 138 | fashion. |
@@ -166,6 +173,9 @@ CONTENTS | |||
166 | is the minimum WCET, and U_max = max{WCET_i/P_i} is the maximum | 173 | is the minimum WCET, and U_max = max{WCET_i/P_i} is the maximum |
167 | utilization[12]. | 174 | utilization[12]. |
168 | 175 | ||
176 | 3.2 Schedulability Analysis for Uniprocessor Systems | ||
177 | ------------------------ | ||
178 | |||
169 | If M=1 (uniprocessor system), or in case of partitioned scheduling (each | 179 | If M=1 (uniprocessor system), or in case of partitioned scheduling (each |
170 | real-time task is statically assigned to one and only one CPU), it is | 180 | real-time task is statically assigned to one and only one CPU), it is |
171 | possible to formally check if all the deadlines are respected. | 181 | possible to formally check if all the deadlines are respected. |
@@ -204,6 +214,9 @@ CONTENTS | |||
204 | time-consuming to be performed on-line. Hence, as explained in Section | 214 | time-consuming to be performed on-line. Hence, as explained in Section |
205 | 4 Linux uses an admission test based on the tasks' utilizations. | 215 | 4 Linux uses an admission test based on the tasks' utilizations. |
206 | 216 | ||
217 | 3.3 Schedulability Analysis for Multiprocessor Systems | ||
218 | ------------------------ | ||
219 | |||
207 | On multiprocessor systems with global EDF scheduling (non partitioned | 220 | On multiprocessor systems with global EDF scheduling (non partitioned |
208 | systems), a sufficient test for schedulability can not be based on the | 221 | systems), a sufficient test for schedulability can not be based on the |
209 | utilizations or densities: it can be shown that even if D_i = P_i task | 222 | utilizations or densities: it can be shown that even if D_i = P_i task |
@@ -249,6 +262,9 @@ CONTENTS | |||
249 | the total utilization is smaller or equal than M then the response times of | 262 | the total utilization is smaller or equal than M then the response times of |
250 | the tasks are limited. | 263 | the tasks are limited. |
251 | 264 | ||
265 | 3.4 Relationship with SCHED_DEADLINE Parameters | ||
266 | ------------------------ | ||
267 | |||
252 | Finally, it is important to understand the relationship between the | 268 | Finally, it is important to understand the relationship between the |
253 | SCHED_DEADLINE scheduling parameters described in Section 2 (runtime, | 269 | SCHED_DEADLINE scheduling parameters described in Section 2 (runtime, |
254 | deadline and period) and the real-time task parameters (WCET, D, P) | 270 | deadline and period) and the real-time task parameters (WCET, D, P) |