8.2: Digraphs (continue)

Digraphs Example 1) TASKSTIMETASKS BEFORE A3 B10C,F,G C2A D4G E5C F8A,H G7H H5

Digraphs Example 1) TASKTASK TI M E TASKS BEFORE A3 B10C,F,G C2A D4G E5C F8A,H G7H H5 End Start A(3) H(5) C(2) G(7) F(8) E(5) B(10) D(4)

Digraphs Example 2) TASKSTIMETASKS BEFORE A3B,C B5 C2 D6A E7C

Digraphs Example 2) TASKTASK TIMETIME TASKS BEFORE A3B,C B5 C2 D6A E7C start end B(5) C(2) A(3) D(6) E(7)

Practice: Digraphs Example 3) TASKSTIMETASKS BEFORE A5C B5C,D C5 D2G E15A,B F6D G2 H2G

Digraphs Example 4) Ten computer programs need to be executed. Three of the program require 4 minutes each to complete, 3 more require 7 minutes each to complete, and 4 of the programs require 15 minutes each to complete. Moreover, none of the 15- minute programs can be started until all of the 4-minute programs have been completed. Draw a digraph for this problem

8.3 Create a schedule using Priority List Steps: –Copy down the priority list (it is given) –Circle the tasks that are ready –Assign the ready tasks to the processors –When a task a complete, check for the next ready tasks When a processor is free, scan the priority list from left to right and assign the next ready task to that processor More than 1 processor is free, the first ready task is assign to 1 free processor and the 2 nd ready task is given to the other processor When tasks are not ready, the processors have to stay “IDLE” A A A

Ex1: Create schedule for 2 people using the given priority list Priority List: E(5), D(2), C(7), B(5), A(6) 2 D 6A5B P2P2 idleidle 5E7C P1P1 Start End A B C D E 2 people can complete these tasks in 13 hours

Ex2: use a different priority list Priority List: A(6), B(5), D(2), C(7), E(5) Start End A B C D E