Beyond nested parallelism: tight bounds on work-stealing overheads for parallel futures

Work stealing is a popular method of scheduling fine-grained parallel tasks. The performance of work stealing has been extensively studied, both theoretically and empirically, but primarily for the restricted class of nested-parallel (or fully strict) computations. We extend this prior work by considering a broader class of programs that also supports pipelined parallelism through the use of parallel futures. Though the overhead of work-stealing schedulers is often quantified in terms of the number of steals, we show that a broader metric, the number of deviations, is a better way to quantify work-stealing overhead for less restrictive forms of parallelism, including parallel futures. For such parallelism, we prove bounds on work-stealing overheads--scheduler time and cache misses--as a function of the number of deviations. Deviations can occur, for example, when work is stolen or when a future is touched. We also show instances where deviations can occur independently of steals and t...

• Type: Conference
• Year: 2009
• Where: SPAA
• Authors: Daniel Spoonhower, Guy E. Blelloch, Phillip B. Gibbons, Robert Harper
• Keywords: Fine-grained Parallel Tasks, Parallel Computing, Parallel Futures, SPAA 2009, Work Stealing