Original vs SPT

SPT Order

Shortest processing time order puts B, then C, then A.

highlighted = computed this step

SPT order

Shortest processing time order is B-C-A.

B−C−AB-C-A
Original and SPTThe chart shows both sequences and the completion table.sequence comparisonimprovement 3OriginalA p=3C=3B p=1C=4C p=2C=606SPTB p=1C=1C p=2C=3A p=3C=606completion tablejoboriginal CSPT CA36B41C63totals 13 -> 10averages 13/3 -> 10/3

B completes

B completes at time 1.

CB=1C_B=1
Original and SPTThe chart shows both sequences and the completion table.sequence comparisonimprovement 3OriginalA p=3C=3B p=1C=4C p=2C=606SPTB p=1C=1C p=2C=3A p=3C=606completion tablejoboriginal CSPT CA36B41C63totals 13 -> 10averages 13/3 -> 10/3

C and A complete

C completes at 3 and A completes at 6.

CC=3CA=6C_C=3\quad C_A=6
Original and SPTThe chart shows both sequences and the completion table.sequence comparisonimprovement 3OriginalA p=3C=3B p=1C=4C p=2C=606SPTB p=1C=1C p=2C=3A p=3C=606completion tablejoboriginal CSPT CA36B41C63totals 13 -> 10averages 13/3 -> 10/3

SPT total

The SPT total completion time is 10.

∑Cj=10\sum C_j=10
Original and SPTThe chart shows both sequences and the completion table.sequence comparisonimprovement 3OriginalA p=3C=3B p=1C=4C p=2C=606SPTB p=1C=1C p=2C=3A p=3C=606completion tablejoboriginal CSPT CA36B41C63totals 13 -> 10averages 13/3 -> 10/3