Average and Scope

Average Flow Time

Average flow time is total completion time divided by the number of jobs.

highlighted = computed this step

Original average

Original average flow time is 13/3.

original average=13/3\text{original average}=13/3
Average and scopeThe same totals also give exact average flow times.averages and scopeimprovement 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 average

SPT average flow time is 10/3.

SPT average=10/3\text{SPT average}=10/3
Average and scopeThe same totals also give exact average flow times.averages and scopeimprovement 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

Same comparison

Average flow time ranks these orders the same way because both averages divide by 3 jobs.

same denominator=3\text{same denominator}=3
Average and scopeThe same totals also give exact average flow times.averages and scopeimprovement 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

Average note

Average flow time is exact here because every job is ready at time zero.

all-ready average flow time\text{all-ready average flow time}
Average and scopeThe same totals also give exact average flow times.averages and scopeimprovement 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