python-rts

This library provides various functions for real time systems related calculations.

NOTE: currently under development. Not all functions are implemented yet. PR's/improvements welcome! Also, this library is limited to periodic tasks and is not planned to be extended furthermore in the future. Feel free to fork and extend on your own!

Content

Types

• PTask - Periodic Task with parameters: Period p, Execution Time e, Phase fi and (relative) Deadline d
• TaskSet - Set of periodic Tasks, takes list of PTask‘s
• Processor - CPU with parameter core count, returns Single-Core Processor by default

Procedures

For Rate Monotonic Scheduling (RMS):

• Scheduling Tests:
  • Liu-Layland Test
  • Rate Monotonous Analysis
  • Hyperbolic Bound
  • Burchard Test
  • SR Test
• Partitioning Procedures:
  • RM Next Fit
  • RM First Fit
  • RM First Fit with Decreasing Utilization
  • RM Small Task
  • RM General Task (TbA)
  • RM Best Fit (TbA)
  • RM Worst Fit (TbA)
• Global Procedures:
  • Adaptive TkC
  • RM Utilization Separation

For Earliest Deadline First Scheduling (EDF):

• Scheduling Tests:
  • u < 1 Test
• Partitioning Procedures:
  • EDF Next Fit
  • EDF First Fit
  • EDF Best Fit (TbA)
• Global Procedures:
  • Global EDF
  • EDF Utilization Separation
  • fpEDF

Comparison

Procedure	Test	Complexity	N/N0
RMNF	LL	O(n)	2.67
RMFF	LL	O(nlogn)	2.23
RMBF	LL	O(nlogn)	2.23
RMFFDU	Hyp. Bd.	O(nlogn)	1.66
RMST	Burch.	O(nlogn)	1/(1-max ui)
EDFNF	u<1	O(n)	?
EDFFF	u<1	O(nlogn)	1.7
EDFBF	u<1	O(nlogn)	1.7

Usage

• Install: pip install git+https://github.com/j-schmied/python-rts.git
• Usage:
  • rts.ipynb (Note: Notebook also uses pandas and plotly)
  • rts.py -> adapt task set on top and run script

Sources

• Jane W. S. Liu. “Real-Time Systems“
• Sudarshan K. Dhall und C. L. Liu. “On a Real-Time Scheduling Problem”
• Ching-Chih Han und Hung-ying Tyan. “A Better Polynomial-Time Schedulability Test for Real-Time Fixed-Priority Scheduling Algorithms”
• Almut Burchard u. a. “Assigning Real-Time Tasks to Homogeneous Multiprocessor Systems”
• Tei-Wei Kuo und Aloysius K. Mok. “Load Adjustment in Adaptive Real-Time Systems”
• C. L. Liu und James W. Layland. “Scheduling Algorithms for Multiprogramming in a Hard-Real-Time Environment”