OpenMP and StarPU Abreast: the Impact of Runtime in Task-Based Block QR Factorization Performance

  • Marcelo Cogo Miletto Universidade Federal do Rio Grande do Sul
  • Lucas Schnorr Universidade Federal do Rio Grande do Sul


Directed Acyclic Graph (DAG) is a high-level abstraction to describe the activities of parallel applications. A DAG contains tasks (nodes) and dependencies (edges) in the task-based programming paradigm. Application performance depends on the choices of the runtime system. Our work intends to evaluate and compare the performance of three different runtime systems, GCC/libgomp, LLVM/libomp, and StarPU for a task-based dense block QR factorization. The obtained results show that while GCC/libgomp achieves up to 5.4% better performance in the best case, it has scalability problems for finegrain problems with large DAGs. LLVM/libomp and StarPU are more scalable, and StarPU is much faster in task creation and submission than the other runtimes.


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MILETTO, Marcelo Cogo; SCHNORR, Lucas. OpenMP and StarPU Abreast: the Impact of Runtime in Task-Based Block QR Factorization Performance. In: SIMPÓSIO EM SISTEMAS COMPUTACIONAIS DE ALTO DESEMPENHO (WSCAD), 20. , 2019, Campo Grande. Anais [...]. Porto Alegre: Sociedade Brasileira de Computação, 2019 . p. 25-36. DOI: