Execution Scheduling at the Server

Once the entire DAG is constructed, it is transferred to a NetSolve computational server. In this first version of request sequencing, the NetSolve agent uses a large granularity and decides which server should execute the entire sequence. We execute a node if all its inputs are available and there are no conflicts with its output parameters. Currently the only mode of execution we support is on a single NetSolve server -- though, that server may be a symmetric multi-processor (SMP).

For data partitioning, we transfer the union of the input parameter sets to the selected server host. This makes input for all nodes, except those which are intermediate output from prior nodes, available for the execution of the sequence. Our scheduling algorithm can be summarized as follows:

  while(problems left to execute)
    execute all problems with satisfied dependencies;
    wait for at least one problem to finish;
    update dependencies;