[PATCH 2/2] Added weak and strong APA definition

[Richi Dubey]

---
 user/glossary/index.rst | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/user/glossary/index.rst b/user/glossary/index.rst
index 5648b39..082483d 100644
--- a/user/glossary/index.rst
+++ b/user/glossary/index.rst
@@ -16,6 +16,22 @@ Glossary
 
   APA
     Arbitrary Processor Affinity
+    
+    Weak APA: Invariant for this model states that for any backlogged task(task not 
+    yet assigned a processor), all the processors in its affinity mask are 
+    occupied by higher-priority tasks. That is, there is no candidate
+    task for preemption scheduled on any of the processors(in a backlogged
+    task's affinity mask) on which the backlogged task may execute. Linux's
+    push-pull scheduling is an example of weak-APA scheduling.
+
+    Strong APA: In this model, on the arrival of a task, every task reachable
+    from the newly arrived task is checked to see if an existing task can
+    be shifted(or deallocated its processor) and newly arrived task can take 
+    its place if the newly arrived task has a higher priority. Similar analysis is
+    done when a task finishes its execution.
+
+    Learn more at: https://people.mpi-sws.org/~bbb/papers/talks/rtss14f.pdf
+
 
   API
     Application Programming Interface
@@ -145,4 +161,4 @@ Glossary
     Waf build system.  For more information see http://www.waf.io/
 
   YAFFS2
-    `Yet Another Flash File System version 2 <https://git.rtems.org/sebh/rtems-yaffs2.git>`_
+    `Yet Another Flash File System version 2 <https://git.rtems.org/sebh/rtems-yaffs2.git>
-- 
2.17.1