Page 75 - DCAP608_REAL TIME SYSTEMS

Real Time Systems

Notes
Figure 7.1: Example for Interrupts and Tasks

Source: http://www.rtos.be/wp-content/uploads/2012/11/interrupts.png

Notes Interrupt Priorities
Interrupt priorities are assigned within the PIC; the system designer usually has full or at
least some control on them (this is PIC platform specific), but how to determine the
priorities of the various tasks? Generally, the more important the task, the higher the
priority it should get assigned. This is true for interrupts and tasks, but more criteria are
important and should be considered.

7.2 Effective Release Time and Deadlines

Sometimes given release times and deadlines of jobs are inconsistent with the precedence
constraints of the jobs. That is the release time of a job may be later than that of its successors, and
its deadline may be earlier than that of its predecessors. So we derive a set of effective release
times and deadlines from these timing constraints together with precedence constraints.

Figure 7.2: Example of Release Time and Deadlines

J (0, 20)
J (4, 9) 6
J (1, 12) 4
J (2, 10) 3
1

J (6, 21)
J (1, 8) 7
J (0, 7) 5
2
Source: ansari.szabist-isb.edu.pk/RTS/RTS0508.ppt

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