RT Schedule home page
RT Schedule is a realtime-schedule generator to create and present simple and
idealised RT schedules from task lists. The purpose is to compute the basic
properties of a task set and create a schedule using the rate monotonic (RM),
earliest deadline first (EDF) and least slack time (LST) / least laxity first (LLF) algorithms. The
program uses simple, idealised systems, since students must be able to
schedule them manually. RT Schedule computes the data and generates clear
graphs for lecture notes and exams. For that purpose, it can also generate LaTeX output. The code was written
by Marc van der
Sluys, of the HAN University of Applied Sciences in Arnhem, The
Netherlands, for the Operating Systems class.
Compiling and installing RT Schedule
RTschedule can be used under the conditions of the GNU General Public Licence
version 3 (GPLv3). The
program is written in Fortran, needs
the libSUFR package and
uses PLplot to generate graphics.
If PLplot is not installed at compile time, the code will be compiled without
graphics support. The default installer
uses CMake. See
the doc/INSTALL
file for installation instructions.
Running RT Schedule
RT Scheduler can be run from the command line, and requires an input file in
order to know what to do. An example input file example.dat is provided. The
task list includes the first occurrence of a task (t), the computational time
(per period; c), the relative deadline (d) and the period (p), all in
arbitrary units. The output from example.dat looks as follows:
$ ./rtschedule example.dat
**************************************************************************************************************
*** GENERAL TASK DATA ***
**************************************************************************************************************
Task list:
Name ti ci di pi
T1 0 1 5 5
T2 0 2 10 10
T3 0 5 15 15
3 lines (processes) read; scheduling for 30 time units.
System load: 0.2000 + 0.2000 + 0.3333 = 0.7333
The task list is SCHEDULABLE in principle (feasible) :-)
Optimal timeslice: 1 time units
Major frame: 30 time units
Minor frame: 5 time units
**************************************************************************************************************
*** RM SCHEDULER ***
**************************************************************************************************************
RM priorities:
Name ti ci di pi prio
T1 0 1 5 5 1
T2 0 2 10 10 2
T3 0 5 15 15 3
RM schedulability test for n=3: SUM Ci/Pi <= n (2^(1/n) - 1):
0.733 <= 0.780, so task set is GUARANTEED to be schedulable with RM.
Timeslice T1 T2 T3 Running Notes
cpu ev cpu ev cpu ev
0-1 _1_ e 2 e 5 e T1
1-2 0 _2_ 5 T2 Switch (task T1 done)
2-3 0 _1_ 5 T2
3-4 0 0 _5_ T3 Switch (task T2 done)
4-5 0 d 0 _4_ T3
5-6 _1_ e 0 3 T1 Switch (task T3: 3>)
6-7 0 0 _3_ T3 Switch (task T1 done)
7-8 0 0 _2_ T3
8-9 0 0 _1_ T3
9-10 0 d 0 d 0 - Switch (task T3 done)
10-11 _1_ e 2 e 0 T1 Switch
11-12 0 _2_ 0 T2 Switch (task T1 done)
12-13 0 _1_ 0 T2
13-14 0 0 0 - Switch (task T2 done)
14-15 0 d 0 0 d -
15-16 _1_ e 0 5 e T1 Switch
16-17 0 0 _5_ T3 Switch (task T1 done)
17-18 0 0 _4_ T3
18-19 0 0 _3_ T3
19-20 0 d 0 d _2_ T3
20-21 _1_ e 2 e 1 T1 Switch (task T3: 1>)
21-22 0 _2_ 1 T2 Switch (task T1 done)
22-23 0 _1_ 1 T2
23-24 0 0 _1_ T3 Switch (task T2 done)
24-25 0 d 0 0 - Switch (task T3 done)
25-26 _1_ e 0 0 T1 Switch
26-27 0 0 0 - Switch (task T1 done)
27-28 0 0 0 -
28-29 0 0 0 -
29-30 0 d 0 d 0 d -
RM ASCII schedule:
T1 # # # # # #
T2 ## ## ##
T3 ## ### #### #
t 0 5 10 15 20 25 30
RM ASCII schedule:
T1 # e# e# e# e# e# e
T2 # # e # # e # # e
T3 # # # # # e # # # # # e
t 0 5 10 15 20 25 30
Graphical schedule saved as example_schedule_RM.png
No deadlines were missed: the system can be scheduled for 30 time units.
16 task switches (1.76 time units per run).
**************************************************************************************************************
*** EDF SCHEDULER ***
**************************************************************************************************************
Timeslice T1 T2 T3 Running Notes
cpu dl ev cpu dl ev cpu dl ev
0-1 _1_ 5 e 2 10 e 5 15 e T1
1-2 0 - _2_ 9 5 14 T2 Switch (task T1 done)
2-3 0 - _1_ 8 5 13 T2
3-4 0 - 0 - _5_ 12 T3 Switch (task T2 done)
4-5 0 - d 0 - _4_ 11 T3
5-6 _1_ 5 e 0 - 3 10 T1 Switch (task T3: 3>)
6-7 0 - 0 - _3_ 9 T3 Switch (task T1 done)
7-8 0 - 0 - _2_ 8 T3
8-9 0 - 0 - _1_ 7 T3
9-10 0 - d 0 - d 0 - - Switch (task T3 done)
10-11 _1_ 5 e 2 10 e 0 - T1 Switch
11-12 0 - _2_ 9 0 - T2 Switch (task T1 done)
12-13 0 - _1_ 8 0 - T2
13-14 0 - 0 - 0 - - Switch (task T2 done)
14-15 0 - d 0 - 0 - d -
15-16 _1_ 5 e 0 - 5 15 e T1 Switch
16-17 0 - 0 - _5_ 14 T3 Switch (task T1 done)
17-18 0 - 0 - _4_ 13 T3
18-19 0 - 0 - _3_ 12 T3
19-20 0 - d 0 - d _2_ 11 T3
20-21 _1_ 5 e 2 10 e 1 10 T1 Switch (task T3: 1>)
21-22 0 - _2_ 9 1 9 T2 Switch (task T1 done)
22-23 0 - _1_ 8 1 8 T2
23-24 0 - 0 - _1_ 7 T3 Switch (task T2 done)
24-25 0 - d 0 - 0 - - Switch (task T3 done)
25-26 _1_ 5 e 0 - 0 - T1 Switch
26-27 0 - 0 - 0 - - Switch (task T1 done)
27-28 0 - 0 - 0 - -
28-29 0 - 0 - 0 - -
29-30 0 - d 0 - d 0 - d -
EDF ASCII schedule:
T1 # # # # # #
T2 ## ## ##
T3 ## ### #### #
t 0 5 10 15 20 25 30
EDF ASCII schedule:
T1 # e# e# e# e# e# e
T2 # # e # # e # # e
T3 # # # # # e # # # # # e
t 0 5 10 15 20 25 30
Graphical schedule saved as example_schedule_EDF.png
No deadlines were missed: the system can be scheduled for 30 time units.
16 task switches (1.76 time units per run).
**************************************************************************************************************
*** LLF SCHEDULER ***
**************************************************************************************************************
Timeslice T1 T2 T3 Running Lax Notes
lax cpu ev lax cpu ev lax cpu ev
0-1 _4_ 1 e 8 2 e 10 5 e T1 4
1-2 - - _7_ 2 9 5 T2 7 Switch (task T1 done)
2-3 - - _7_ 1 8 5 T2 7
3-4 - - - - _7_ 5 T3 7 Switch (task T2 done)
4-5 - - d - - _7_ 4 T3 7
5-6 _4_ 1 e - - 7 3 T1 4 Switch (task T3: 3>)
6-7 - - - - _6_ 3 T3 6 Switch (task T1 done)
7-8 - - - - _6_ 2 T3 6
8-9 - - - - _6_ 1 T3 6
9-10 - - d - - d - - - - Switch (task T3 done)
10-11 _4_ 1 e 8 2 e - - T1 4 Switch
11-12 - - _7_ 2 - - T2 7 Switch (task T1 done)
12-13 - - _7_ 1 - - T2 7
13-14 - - - - - - - - Switch (task T2 done)
14-15 - - d - - - - d - -
15-16 _4_ 1 e - - 10 5 e T1 4 Switch
16-17 - - - - _9_ 5 T3 9 Switch (task T1 done)
17-18 - - - - _9_ 4 T3 9
18-19 - - - - _9_ 3 T3 9
19-20 - - d - - d _9_ 2 T3 9
20-21 _4_ 1 e 8 2 e 9 1 T1 4 Switch (task T3: 1>)
21-22 - - _7_ 2 8 1 T2 7 Switch (task T1 done)
22-23 - - _7_ 1 7 1 T2 7 Choice: keep same task
23-24 - - - - _6_ 1 T3 6 Switch (task T2 done)
24-25 - - d - - - - - - Switch (task T3 done)
25-26 _4_ 1 e - - - - T1 4 Switch
26-27 - - - - - - - - Switch (task T1 done)
27-28 - - - - - - - -
28-29 - - - - - - - -
29-30 - - d - - d - - d - -
LLF ASCII schedule:
T1 # # # # # #
T2 ## ## ##
T3 ## ### #### #
t 0 5 10 15 20 25 30
LLF ASCII schedule:
T1 # e# e# e# e# e# e
T2 # # e # # e # # e
T3 # # # # # e # # # # # e
t 0 5 10 15 20 25 30
Graphical schedule saved as example_schedule_LLF.png
No deadlines were missed: the system can be scheduled for 30 time units.
16 task switches (1.76 time units per run).
Contact
You can contact the author (preferably through email) via this page.
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