Also, it was proved that List scheduling is optimum online algorithm for 2 and 3 machines.

Some known list scheduling strategies are :

The simplest algorithm to find a topological sort is frequently used and is known as list scheduling.

It descends from list scheduling algorithms.

The basic idea of list scheduling is to make an ordered list of processes by assigning them some priorities, and then repeatedly execute the following two steps until a valid schedule is obtained :

If you have a schedule which is p-approximation for weighted completion time on one machine, list scheduling using that one machine schedule as the list gives a (p+1)-approximation for the parallel machines case.