From 16c326c65237e0eca300008ead61dcc1f5dc6e76 Mon Sep 17 00:00:00 2001 From: Richi Dubey Date: Tue, 30 Jun 2020 09:01:22 +0200 Subject: c-user: Add APA terms to glossary --- c-user/glossary.rst | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) (limited to 'c-user') diff --git a/c-user/glossary.rst b/c-user/glossary.rst index 86350a8..c3907f5 100644 --- a/c-user/glossary.rst +++ b/c-user/glossary.rst @@ -1,5 +1,6 @@ .. SPDX-License-Identifier: CC-BY-SA-4.0 +.. Copyright (C) 2020 Richi Dubey (richidubey@gmail.com) .. Copyright (C) 2017, 2019 embedded brains GmbH (http://www.embedded-brains.de) .. Copyright (C) 1988, 1998 On-Line Applications Research Corporation (OAR) @@ -16,6 +17,14 @@ Glossary A term used to describe an object which has been created by an application. + APA + This term is an acronym for Arbitrary Processor Affinity. APA schedulers + allow a thread to have an arbitrary affinity to a processor set, rather than + a restricted mapping to only one processor of the set or the ability to run + on all processors of the set. + + It has two variants, :term:`Weak APA` and :term:`Strong APA`. + aperiodic task A task which must execute only at irregular intervals and has only a soft deadline. @@ -777,6 +786,17 @@ Glossary :term:`return value` to indicate a successful operation or error conditions. + Strong APA + Strong APA is a specialization of :term:`APA`. Schedulers which implement + strong APA recursively searches for a processor in the :term:`thread`'s + affinity set, whenever a thread becomes ready for execution, followed by the + processors in the affinity set of threads that are assigned the processor + present in the ready thread's affinity set. This is done to find a thread to + processor mapping that does not violate the priority ordering and to provide + a thread to processor mapping with a higher total priority of the threads + allocated a processor. Similar analysis is done when a thread blocks. See + also :cite:`Cerqueira:2014:LPA`. + suspend A term used to describe a task that is not competing for the CPU because it has had a ``rtems_task_suspend`` directive. @@ -905,6 +925,14 @@ Glossary Message queues, regions, and semaphores have a wait queue associated with them. + Weak APA + Weak APA is a specialization of :term:`APA`. This refers to Linux's push + and pull implementation of APA model. When a :term:`thread` becomes ready + for execution, it is allocated a processor if there is an idle processor, or + a processor executing a lower priority thread in its affinity set. Unlike + :term:`Strong APA`, no thread is migrated from its processor to find a thread + to processor mapping. See also :cite:`Cerqueira:2014:LPA`. + YAML This term is an acronym for `YAML Ain't Markup Language `_. -- cgit v1.2.3