Available schedulers

The available M workflow schedulers are:

• A basic scheduler (option -basic or default choice): this scheduler manages the precedence constraints between the tasks. The priority between tasks within a dag is set according (Heterogeneous Earliest Finish Time) HEFT [24] heuristic. When a task is ready to be executed (i.e., the preceding tasks are completed) the ready task with the higher HEFT rank is sent to the client for execution without specifying a ressource. Then the client performs a standard DIET request that will use the scheduler configured by the SeD.

• A Multi-HEFT scheduler (option -heft): this scheduler applies the HEFT heuristic to all workflows submitted by different clients to the M. This means that the priorities assigned by the HEFT heuristic are used to order the tasks of all dags processed by the M and following this order the tasks are mapped to the first available ressource.

• A Multi-AgingHEFT scheduler (option -aging_heft): this scheduler is similar to Multi-HEFT but it applies a correction factor to the priorities calculated by the HEFT algorithm. This factor is based on the age of the dag ie the time since it was submitted to the scheduler. Compared to Multi-HEFT this scheduler will increase the priority of the tasks of a workflow that has been submitted earlier than other dags.

• A FOFT (Fairness on Finish Time) scheduler (option -fairness): this scheduler uses another heuristic to apply a correction factor to the priorities calculated by the HEFT algorithm. This factor is based on the slowdown of the dag that is calculated by comparing the earliest finish time of the tasks in the same environment without any other concurrent workflow and the actual estimated finish time.