Wed 17 Jun 2015 14:00 - 14:25 at PLDI Main BLUE (Portland 254-255) - Parallelism Chair(s): Sara Baghsorkhi

Matching program parallelism to platform parallelism using thread selection is difficult when the environment and available resources dynamically change. Existing compiler or runtime approaches are typically based on a one-size fits all policy.There is little ability to either evaluate or adapt the policy when encountering new external workloads or hardware resources. This paper focuses on selecting the best number of threads for a parallel application in dynamic environments. It develops a new scheme based on a mixture of experts approach. It learns online which, of a number of existing policies, or experts, is best suited for a particular environment without having to try out each policy. It does so by using a novel environment predictor as a proxy for the quality of an expert thread selection policy. Additional expert policies can easily be added and are selected only when appropriate. We evaluate our scheme in environments with varying external workloads and hardware resources. We then consider the case when workloads use affinity scheduling or are themselves adaptive and show that our approach, in all cases, outperforms existing schemes and surprisingly improves workload performance. On average, we improve 1.69x over OpenMP default, 1.36x over an online scheme, 1.27x over an offline policy and 1.21x over a state-of-art analytic model. Determining the right number and type of experts is an open problem and our initial analysis shows that adding more experts improves accuracy and performance.

Wed 17 Jun
Times are displayed in time zone: Tijuana, Baja California change

14:00 - 15:40: ParallelismResearch Papers at PLDI Main BLUE (Portland 254-255)
Chair(s): Sara BaghsorkhiIntel Labs
14:00 - 14:25
Talk
Celebrating Diversity: A Mixture of Experts Approach for Runtime Mapping in Dynamic Environments
Research Papers
Murali Krishna EmaniThe University of Edinburgh, Michael F. P. O'BoyleUniversity of Edinburgh
Media Attached
14:25 - 14:50
Talk
Efficient Execution of Recursive Programs on Commodity Vector Hardware
Research Papers
Bin RenPacific Northwest National Laboratories, Youngjoon JoPurdue University, Sriram KrishnamoorthyPacific Northwest National Laboratories, Kunal AgrawalWashington University in St. Louis, Milind KulkarniPurdue University
Media Attached
14:50 - 15:15
Talk
Loop and Data Transformations for Sparse Matrix Code
Research Papers
Anand VenkatUniversity of Utah, Mary HallUniversity of Utah, Michelle StroutColorado State University
Media Attached
15:15 - 15:40
Talk
Synthesizing Parallel Graph Programs via Automated Planning
Research Papers
Dimitrios PrountzosThe University of Texas at Austin, Texas, USA, Roman ManevichBen-Gurion University of the Negev, Keshav PingaliUniversity of Texas, Austin
Media Attached