Fast Static Scheduling Algorithm for DAGs on an Unbounded Number of Processors

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Fast Static Scheduling Algorithm for DAGs on an
Unbounded Number of Processors

• SpeakerSi-Wen Hung
• AdvisorDr. Sao-Jie Chen

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Outline

• Introduction
• Scheduling Classification
• EZ
• DSC
• Clan
• Comparison

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Introduction

• Scheduling
• Assign all the tasks to PE
• Minimize the total processing

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Introduction

• Tasks graph
• Communication overhead

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Introduction
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Introduction
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Introduction

• Tree-structured task graph

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Introduction

• Critical path heuristic
• In order to reduce the critical path by
  clustering
• DSC
• MCP
• EZ

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Introduction

• Assumptions
• Task duplication is not allowed
• The number of available processors is unlimited
• The task execution is triggered by the arrival of
  all data and at the completion of its execution
  the data are send in parallel to successor tasks.

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Algorithm.1

• Clustering steps by Sarkars algorithm(EZ)
• Initially each task is in a separate cluster
• Sort all the edges from high cost to low cost
• For each edge from the sorted edge list
• If set the edge to zero cost would reduce
  parallel time
• If yes , set the two nodes of the edge to the
  same cluster

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Algorithm.1

• Example

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Algorithm.2

• Dominant sequence clustering algorithm (DSC)
• Partial free list (PFL),Free list (FL)
• Select the highest priority of node from PHL and
  FL
• If set the node to the same cluster would reduce
  parallel time
• If yes , set the two nodes of the edge to the
  same cluster
• Otherwise, open new cluster for the node

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Algorithm.2

• Example

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Clan

• Type
• Linear
• Independent
• Parse Tree
• Hierarchical view

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Clan

• Parse Tree
• Hierarchical view

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Clan

• Multi-Stage Decision Graph
• Find the shortest path

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Comparison

• Granularity Analysis
• 420 test graph
• Speedup lt 1

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Comparison

• Normalized Relative Parallel Time
• Average speed up

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Comparison

• Efficiency of the algorithm

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Conclusion

• Clan has high speed up ,but more complexity at
  low granularity
• Clan is not better than other at high granularity
• Clan suit the cases of wide range of granularity
  or low granularity

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References

• A. Gerasoulis and T. Yang, "A Fast Static
  Scheduling Algorithm for DAGs on a unbounded
  Number of Processors," Proc. of
  Supercomputing'91, (Nov. 1991), pp.633-642.
• T. Yang and A. Gerasoulis, "A Fast Static
  Scheduling Algorithm for DAGs on an Unbounded
  Number of Processors", Proc. Supercomputing '91,
  pp. 633-642 (1991).
• A. A. Khan, C. L. McCreary and Y. Gong, A
  Numerical Comparative Analysis of Partitioning
  Heuristics for Scheduling Task Graphs on
  Multiprocessors, October 21, 1993.

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