Towards Automated Tuning of Parallel Programs

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Towards Automated Tuning of Parallel Programs

• Jeffrey K. Hollingsworth
• hollings_at_cs.umd.edu
• Department of Computer Science
• University of Maryland, College Park, MD 20742

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Why Automated Performance Tuning?

• Software commonly have parameters that impact
  their performance.
• Optimal parameter values are usually variable and
  un-predictable.
• Automated Parameter tuning can be used for
  adaptive parameter tuning in complex software.

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Automated Performance Tuning

• Goal Maximize achieved performance
• Problems
• Large number of parameters to tune
• Shape of objective function unknown
• Multiple libraries and coupled applications
• Analytical model may not be available
• Requirements
• Runtime tuning for long running programs
• Dont try too many configurations
• Avoid gradients

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Active Harmony

• Runtime performance optimization
• Can also support training runs
• Automatic library selection (code)
• Monitor library performance
• Switch library if necessary
• Automatic performance tuning (parameter)
• Monitor system performance
• Adjust runtime parameters
• Hooks for Compiler Frameworks
• Working to integrate USC/ISI Chill
• Looking at others too

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Example Cluster Based Web Server

• 3-tier system
• Harmony Provides
• Parameter updates for DB, and App Severs
• TPC-W Benchmark
• Transactional web benchmark
• Mimic operations of an e-commerce site
• Uses Java implementation from Univ. of Wisconsin
• Performance metrics
• Web Interaction Per Second (WIPS)

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Cluster-Based Web Service Tuning
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Importance of various parameters
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A Bit More About Harmony Search

• Pre-execution
• Sensitivity Discovery Phase
• Used to Order not Eliminate search dimensions
• Online
• Use Parallel Rank Order Search
• Different configurations on different nodes

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Benefits of Searching in Parallel

• Performance for Two Programs
• High Performance Linpack
• POP Ocean Code

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Integrating Compiler Transformations
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Performance of Matrix Multiply ActiveHarmony
CHiLL vs ATLAS and MKL
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Must Coordinate Auto Tuners

• Problem Warring auto tuning systems
• Multiple components auto tuning at once
• Tuning based on multiple changes at once
• Solution
• Need some level of coordination
• Possible Answer
• Exposing different tuning systems
• Part of PERI Auto-tuning Effort

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Conclusion

• Active Harmony
• An infrastructure for runtime tuning
• Automatic tuning and environment adaptation
• It works !
• Auto Tuning Integration
• Need to integrate multiple tools
• Compilers, runtime, application

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Acknowledgements

• Coding and Experiments
• I-Hsin Chung (IBM Watson)
• Vahid Tabatabaee
• Ananta Tiwari
• Chill Integration Effort
• Marry Hall (Utah)
• Chun Chen (USC/ISI)
• Jacqueline Chame (USC/ISI)
• Funding
• DOE PERC/PERI
• NSF
• LTS (DoD)