Abstract

Parallel functional programs with implicit communication often generate purely hierarchical communication topologies during execution: communication only happens between parent and child processes. Messages between siblings must be passed via the parent. This causes inefficiencies that can be avoided by enabling direct communication between arbitrary processes. The Eden parallel functional language provides dynamic channels to implement arbitrary communication topologies. This paper analyses the impact of dynamic channels on Eden’s topology skeletons, i.e. skeletons which define process topologies such as rings, toroids, or hypercubes. We compare topology skeletons with and without dynamic channels with respect to the number of messages. Our case studies confirm that dynamic channels usually decrease the number of messages by up to 50 % and can reduce runtime by up to 50%. Detailed analysis of Eden TV (trace viewer) execution profiles reveals the reasons for these substantial runtime gains. 1.

Citations