EARTH--MANNA

Applications on a multithreaded architecture: A case study with EARTH--MANNA. Multithreading offers benefits with respect to the formulation of irregular dynamic programs and their dynamic scheduling, load balancing and interaction. Furthermore, low-cost communication on distributed-memory machines by remote-memory access is provided by some systems for efficient communication. EARTH is one of the few systems which combines both, while most other systems either focus on communication or provide multithreading in shared-memory environments. Dynamic irregular applications are often awkward to parallelize on distributed memory when using SPMD style programming via MPI and show different requirements for formulation. In addition, dynamic irregular applications also may show a fairly tight data coupling. Systems like EARTH are beneficial then, because they specifically support large number of small data exchanges by providing short startup times and the tolerance of even small latencies (offering very fine-grain threads). However, static regular applications with tight data coupling are supported too. On the example of EARTH, this paper investigates the benefits of low-cost communication and multithreading, parallelizing three AI applications with medium to high communication intensity. We present experimental results obtained on the MANNA machine.