The HIPERFIT July 2013 seminar is planned for Tuesday, July 2 from 14:00 to 15:30 at the DIKU small auditorium (Lille Aud), where we will have two presentations by Troels Henriksen and Brian Vinter:

  • 14:00-14:30. A T2 Graph-Reduction Approach To Fusion. (Troels Henriksen, HIPERFIT, DIKU).

  • 14:30-15:00. BPU Simulator. (Brian Vinter, HIPERFIT, NBI).

  • 15:00-15:30. A light refreshment, served by HIPERFIT.

Abstracts for the talks follow below.

We look forward to see you at the seminar!

Best Regards,

Martin Elsman

HIPERFIT Center Manager

A T2 Graph-Reduction Approach To Fusion

Troels Henriksen, HIPERFIT, DIKU

14:00-14:30 July 2, 2013

The (DIKU) small auditorium at Universitetsparken 1 (UP1)

Abstract: Fusion is one of the most important code transformations as it has the potential to substantially optimize both the memory hierarchy time overhead and (sometimes asymptotically) the space requirement. In imperative languages, the legality of loop-fusion is typically verified by dependency analysis on arrays applied at loop-nest level. Such analysis, however, has often been labeled as “heroic effort” and, if at all, is supported only in its simplest and most conservative form in industrial compilers. In functional languages, fusion is naturally and more easily derived as a producer-consumer relation between program constructs that expose a richer, higher-order algebra of program invariants, such as the map-reduce list homomorphisms. Related implementations in the functional context typically apply fusion only when the to-be-fused producer is used exactly once, i.e., in the consumer. This guarantees that the transformation is conservative: the resulting program does not duplicate computation. We show that the above restriction is more conservative than needed, and present a structural-analysis algorithm, inspired from the T1 -T2 transformation for reducible data flow, that enables fusion even in some cases when the producer is used in different consumers and without duplicating computation. We report an implementation of the fusion algorithm for a functional-core language, named L0 , which is intended to support nested parallelism across regular multi-dimensional arrays. We succinctly describe L0’s semantics and the compiler infrastructure on which the fusion transformation relies.

Troels Henriksen is an MSc student at DIKU, employed in the HIPERFIT research center, and working on the implementation and design of the HIPERFIT parallel-functional programming language L.

BPU Simulator

Brian Vinter, HIPERFIT, NBI

14:30-15:00 July 2, 2013

The (DIKU) small auditorium at Universitetsparken 1 (UP1)

Abstract: A number of scientific applications start their life as a Matlab prototype that is later re-implemented in a low level programming language, typically C++ or Fortran for the sake of performance. Bohrium is a project that seeks to eliminate both the cost and the potential errors introduced in that process. Our goal is to support all execution platforms, and in this work we introduce the Bohrium Processing Unit, BPU, which will be the FPGA backend for Bohrium. The BPU is modeled as a PyCSP application, and the clear advantages of using CSP for simulating a new CPU is described. The current PyCSP simulator is able to simulate 220 Monte Carlo simulations in less than 35 seconds in the smallest BPU simulation. Joined work with Martin Rehr and Kenneth Skovhede, Niels Bohr Institute.

Brian Vinter is professor at Niels Bohr Institute (NBI) and has many years of research experience within the areas of grid computing, supercomputing, multicore architectures, and metods for transparent utilization of parallellism.