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Static Process Scheduling

Static Process Scheduling. Martha Garcia. Static Process scheduling. Goals of Static Process Scheduling Types of Static Process Scheduling Future Research References. Static Process scheduling. GOALS :

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Static Process Scheduling

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  1. Static Process Scheduling Martha Garcia

  2. Static Process scheduling • Goals of Static Process Scheduling • Types of Static Process Scheduling • Future Research • References

  3. Static Process scheduling GOALS : • Given a set or partially ordered tasks, define a mapping of processes to processors before the execution of the processes. • Cost model:CPU cost and communication cost, both should be specified in prior • Minimize the overall finish time on a non-preemptive(can not be interrupted) multiprocessor system (of identical processors) -Except for some very restricted cases, scheduling to optimize the makespand are NP-Complete -Heuristic solutions are usually proposed.

  4. Static Process scheduling Two Types : • Precedence Process Model • Communication Process Model

  5. Static Process scheduling-Precedence PROCESS MODEL • Precedence Process Model : • Program is represented by a DAG(Directed Acyclic Graph). Direct edges represent the precedence relationship. • The longest execution path in the DAG often used to compare the performance of a heuristic algorithm. I K J L [Chow and Johnson 1997]

  6. Static Process scheduling- Precedence PROCESS MODEL • Precedence constraints among tasks in a program are explicitly specified. • Scheduling goal: minimize the makespan time Communication overhead for A(P1) and E(P3)= 4 * 2 = 8 Communication overhead for one message Execution time No. of messagesto communicate [Chow and Johnson 1997]

  7. Static Process scheduling- Precedence PROCESS MODEL Algorithms: • List Scheduling (LS): Communication overhead is not considered. Using a simple greedy heuristic: No processor remains idle if there are some tasks available that it could process. • Extended List Scheduling (ELS): the actual scheduling results of LS with communication consideration. • Earliest Task First scheduling (ETF): the earliest schedulable task (with communication delay considered) is scheduled first. [Chow and Johnson 1997]

  8. Static Process scheduling- Precedence PROCESS MODEL Makespan Calculation for LS, ELS, and ETF [Chow and Johnson 1997]

  9. Static Process scheduling- cOMMUNICATIONPROCESS MODEL Communication Process Model • There are no precedence constrains among processes • modeled by a undirected graph G, node represent processes and weight on the edge is the amount of communication messages between two connected processes. • Process execution cost might be specified some times to handle more general cases. • Scheduling goal: maximize the resource utilization [Chow and Johnson 1997]

  10. Static Process scheduling- cOMMUNICATION PROCESS MODEL • the problem is to find an optimal assignment of m process to P processors with respect to the target function: • P: a set of processors. ej(pi): computation cost of execution process pi in processor Pj. • ci,j(pi,pj): communication overhead between processes pi and pj. • Assume a uniform communicating speed between processors. [Chow and Johnson 1997]

  11. Static Process scheduling- cOMMUNICATION PROCESS MODEL • This is referred as Module Allocation problem. It is NP-complete except for a few cases: • For P=2, Stone suggested an polynomial time solution using Ford-Fulkerson’s maximum flow algorithm. • Known results: The mapping problem for an arbitrary number of processors is NP-complete. [Chow and Johnson 1997]

  12. Static Process scheduling- cOMMUNICATION PROCESS MODEL • Stone’s two-processor model to achieve minimum total execution and communication cost • Example: • Partition the graph by drawing a line cutting through some edges • Result in two disjoint graphs, one for each process • Set of removed edges  cut set • Cost of cut set  sum of weights of the edges • Total inter-process communication cost between processors • Of course, the cost of cut sets is 0 if all processes are assigned to the same node • Computation constraints (no more k, distribute evenly…) • Example: • Maximum flow and minimum cut in a commodity-flow network • Find the maximum flow from source to destination [Chow and Johnson 1997]

  13. Static Process scheduling- cOMMUNICATION PROCESS MODEL Maximum Flow Algorithm in Solving the Scheduling Problem [Chow and Johnson 1997]

  14. Static Process scheduling- cOMMUNICATION PROCESS MODEL Minimum-Cost Cut Only the cuts that separate A and Bare feasible [Chow and Johnson 1997]

  15. Static Process scheduling Future Research : • UseAI techniques for Static Scheduling : Genetic Algorithm

  16. Static Process scheduling References : • Design Optimization of Time – and Cost – Constrained Fault – Tolerant Distributed Embedded Systems.- ViacheslavIzosimov, Paul Pop. PetruEles, ZeboPeng • A Static Task Scheduling Framework for Independent Tasks Accelerated using a Shared Graphics Processing Unit.- Teng Li, VikramK.Narayana, Tarek El-Ghazawi, IEEE 2011 • MAPPLE chip: a processing element for a static scheduling centric multiprocessor.- Kenta Yasufuku, Riku Ogawa, Keisure Iwai, HideharuAmanu, IEEE 2003

  17. Static Process scheduling • Thank you!!

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