[rtems-docs commit] c-user/rate_monotonic_manager.rst: Use Latex math for utilization formulas

Joel Sherrill joel at rtems.org
Tue Apr 25 18:16:27 UTC 2017


Module:    rtems-docs
Branch:    master
Commit:    c8b674582502994299a3a47ad0962c6d46986f36
Changeset: http://git.rtems.org/rtems-docs/commit/?id=c8b674582502994299a3a47ad0962c6d46986f36

Author:    Joel Sherrill <joel at rtems.org>
Date:      Fri Mar 10 15:26:35 2017 -0600

c-user/rate_monotonic_manager.rst: Use Latex math for utilization formulas

---

 c-user/rate_monotonic_manager.rst | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/c-user/rate_monotonic_manager.rst b/c-user/rate_monotonic_manager.rst
index 05eb59f..96539ed 100644
--- a/c-user/rate_monotonic_manager.rst
+++ b/c-user/rate_monotonic_manager.rst
@@ -266,22 +266,21 @@ Processor Utilization Rule
 .. index:: RMS Processor Utilization Rule
 
 The Processor Utilization Rule requires that processor utilization be
-calculated based upon the period and execution time of each task.  The fraction
-of processor time spent executing task index is ``Time(index) /
-Period(index)``.  The processor utilization can be calculated as follows:
+calculated based upon the period and execution time of each task.
+The fraction of processor time spent executing task index is ``Time(i)
+/ Period(i)``.  The processor utilization can be calculated as follows
+where n is the number of tasks in the set being analyzed:
 
-.. code-block:: c
+.. math::
 
-    Utilization = 0
-    for index = 1 to maximum_tasks
-        Utilization = Utilization + (Time(index)/Period(index))
+    Utilization = \sum_{i=1}^{n} Time_i/Period_i
 
 To ensure schedulability even under transient overload, the processor
 utilization must adhere to the following rule:
 
-.. code-block:: c
+.. math::
 
-    Utilization = maximum_tasks * (2**(1/maximum_tasks) - 1)
+    maximumUtilization = n * (2^{\frac{1}{n}} - 1)
 
 As the number of tasks increases, the above formula approaches ln(2) for a
 worst-case utilization factor of approximately 0.693.  Many tasks sets can be




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