Least Laxity First

Least Laxity First, also known as planning according to leeway , is a scheduling method especially suitable for multiprocessor computers . However, it is based on the simplified assumption that every process has the same execution time on every available processor and that individual processes are not tied to a specific processor, although this is especially the case with embedded systems .

Procedure

In this method, the process scheduler first selects those processes that have the least leeway. The scope of a process is understood to be the time difference between the time limit up to the point in time at which the process must be fully executed, minus the time the process is ready and the execution time.

Formula: ${\displaystyle l_{j}=d_{j}-r_{j}-p_{j}}$

${\displaystyle l_{j}}$: Laxity of task j (leeway)

${\displaystyle d_{j}}$: Deadline of task j (latest completion date)

${\displaystyle r_{j}}$: Release time of task j (ready time)

${\displaystyle p_{j}}$: Processing time of task j (execution time)

This scheduling method tries to execute every process as late as possible.

fitness

This procedure is ideal for interruptible processes.

It is best suited for systems with many aperiodic tasks.

disadvantage

This method results in a high computational effort. Furthermore, many task changes may be necessary.