The Impact of Dynamic Channels on Functional Topology Skeletons

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.

Comparing and Optimising Parallel Haskell Implementations for Multicore Machines

“…Finally, the ring skeleton illustrates a different class of skeletons. Rather than capturing algorithmic structure, topology skeletons, explicitly represent the parallel interaction between processes in a regular topology [20], [21], [22]. 1) Implementing Skeletons in Eden.…”

Parallel Coordination Made Explicit in a Functional Setting

“…There are however situations where Eden's implicit concurrency and eagerness can lead to unwanted behaviour, and the source code usually does not clearly indicate the errors. A ring of interconnected processes can be defined using Eden channels [1]. Fig.…”