[rtems-central commit] glossary: Priorities

[Sebastian Huber]

Module:    rtems-central
Branch:    master
Commit:    8b4f848354868a6550c29ae6d6482db48ce0fc8a
Changeset: http://git.rtems.org/rtems-central/commit/?id=8b4f848354868a6550c29ae6d6482db48ce0fc8a

Author:    Sebastian Huber <sebastian.huber at embedded-brains.de>
Date:      Mon Sep 13 09:53:17 2021 +0200

glossary: Priorities

---

 spec-glossary/glossary/priority-higher.yml | 13 +++++++++++++
 spec-glossary/glossary/priority-lower.yml  | 13 +++++++++++++
 spec-glossary/glossary/priority-task.yml   | 11 ++++++++---
 spec-glossary/glossary/priority.yml        | 18 ++++++++++++++++--
 4 files changed, 50 insertions(+), 5 deletions(-)

diff --git a/spec-glossary/glossary/priority-higher.yml b/spec-glossary/glossary/priority-higher.yml
new file mode 100644
index 0000000..53bc4fa
--- /dev/null
+++ b/spec-glossary/glossary/priority-higher.yml
@@ -0,0 +1,13 @@
+SPDX-License-Identifier: CC-BY-SA-4.0 OR BSD-2-Clause
+copyrights:
+- Copyright (C) 2021 embedded brains GmbH (http://www.embedded-brains.de)
+enabled-by: true
+glossary-type: term
+links:
+- role: glossary-member
+  uid: ../glossary-general
+term: lower priority
+text: |
+  A ${task:/term} ``L`` has a lower ${priority:/term} than a task ``H``, if
+  task ``L`` is less important than task ``H``.
+type: glossary
diff --git a/spec-glossary/glossary/priority-lower.yml b/spec-glossary/glossary/priority-lower.yml
new file mode 100644
index 0000000..dc42f79
--- /dev/null
+++ b/spec-glossary/glossary/priority-lower.yml
@@ -0,0 +1,13 @@
+SPDX-License-Identifier: CC-BY-SA-4.0 OR BSD-2-Clause
+copyrights:
+- Copyright (C) 2021 embedded brains GmbH (http://www.embedded-brains.de)
+enabled-by: true
+glossary-type: term
+links:
+- role: glossary-member
+  uid: ../glossary-general
+term: higher priority
+text: |
+  A ${task:/term} ``H`` has a higher ${priority:/term} than a task ``L``, if
+  task ``H`` is more important than task ``L``.
+type: glossary
diff --git a/spec-glossary/glossary/priority-task.yml b/spec-glossary/glossary/priority-task.yml
index b2bfccf..c0a4982 100644
--- a/spec-glossary/glossary/priority-task.yml
+++ b/spec-glossary/glossary/priority-task.yml
@@ -8,10 +8,15 @@ links:
   uid: ../glossary-general
 term: task priority
 text: |
-  A task priority of a ${task:/term} determines its importance relative to
-  other tasks.  The scheduler use task priorities to determine which
-  ${readytask:/term} gets a processor allocated, see ${scheduledtask:/term}.  The
+  A task ${priority:/term} of a ${task:/term} determines its importance
+  relative to other tasks.
+  
+  The scheduler use task priorities to determine which ${readytask:/term} gets
+  a processor allocated, see ${scheduledtask:/term}.  The
   ${priority-eligible:/plural} of a task define the position of the task in a
   ${waitqueue:/term} which uses the priority discipline.  Each task has at
   least the ${priority-real:/term}.
+
+  Task priorities are used in ${waitqueue:/plural} which use the priority
+  discipline to determine the dequeueing order of tasks.
 type: glossary
diff --git a/spec-glossary/glossary/priority.yml b/spec-glossary/glossary/priority.yml
index b5efb9d..613a660 100644
--- a/spec-glossary/glossary/priority.yml
+++ b/spec-glossary/glossary/priority.yml
@@ -9,6 +9,20 @@ links:
 term: priority
 text: |
   The priority is a mechanism used to represent the relative importance of an
-  element in a set of items.  RTEMS uses ${priority-task:/plural} to determine
-  which ${task:/term} should execute.
+  element in a set of items.
+
+  For example, ${rtems:/term} uses ${priority-task:/plural} to determine which
+  ${task:/term} should execute on a processor.  In RTEMS, priorities are
+  represented by non-negative integers.
+
+  For the Classic ${api:/term}, if a numerical priority value ``A`` is greater
+  than a numerical priority value ``B``, then ``A`` expresses a
+  ${priority-lower:/term} than ``B``.  If a numerical priority value ``C`` is
+  less than a numerical priority value ``D``, then ``C`` expresses a
+  ${priority-higher:/term} than ``D``.
+  
+  For the ${posix:/term} API, if a numerical priority value ``R`` is less than
+  a numerical priority value ``S``, then ``R`` expresses a lower priority than
+  ``S``.  If a numerical priority value ``T`` is greater than a numerical
+  priority value ``U``, then ``T`` expresses a higher priority than ``U``.
 type: glossary