Chapel unblocked: recent communication optimizations in Chapel

This talk will highlight communication optimizations made to the Chapel compiler and runtime over the past year. It will focus on improvements to core benchmarks that have benefited from fine-grained and bulk communication optimizations as well as remote task-spawning improvements. Several benchmarks including HPC Challenge (HPCC) RandomAccess, HPCC Stream Triad, and an integer sort code ISx will be briefly introduced, and a relevant performance optimization will be showcased. These benchmarks represent core idioms that are common in many HPC applications. Performance results on up to 1,024 nodes (25,000 cores) will demonstrate that with each release Chapel is becoming more competitive against hand tuned MPI+OpenMP, SHMEM, and UPC.