Computer Science Technical Reports
CS at VT

Dynamic Multigrain Parallelization on the Cell Broadband Engine

Blagojevic, Filip and Nikolopoulos, Dimitrios and Stamatakis, Alexandros and Antonopoulos, Christos (2006) Dynamic Multigrain Parallelization on the Cell Broadband Engine . Technical Report TR-06-24, Computer Science, Virginia Tech.

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This paper addresses the problem of orchestrating and scheduling parallelism at multiple levels of granularity on heterogeneous multicore processors. We present policies and mechanisms for adaptive exploitation and scheduling of multiple layers of parallelism on the Cell Broadband Engine. Our policies combine event-driven task scheduling with malleable loop-level parallelism, which is exposed from the runtime system whenever task-level parallelism leaves cores idle. We present a runtime system for scheduling applications with layered parallelism on Cell and investigate its potential with RAxML, a computational biology application which infers large phylogenetic trees, using the Maximum Likelihood (ML) method. Our experiments show that the Cell benefits significantly from dynamic parallelization methods, that selectively exploit the layers of parallelism in the system, in response to workload characteristics. Our runtime environment outperforms naive parallelization and scheduling based on MPI and Linux by up to a factor of 2.6. We are able to execute RAxML on one Cell four times faster than on a dual-processor system with Hyperthreaded Xeon processors, and 5--10\% faster than on a single-processor system with a dual-core, quad-thread IBM Power5 processor.

Item Type:Departmental Technical Report
Keywords:Cell Broadband Engine, RAxML, Parallel Programing, Dynamic Scheduling
Subjects:Computer Science > Parallel Computation
Computer Science > Bioinformatics
ID Code:927
Deposited By:Blagojevic, Filip
Deposited On:23 October 2006