Software-Pipelining on Multi-Core Architectures

Alban Douillet1 and Guang R. Gao2
1Hewlett-Packard, 2University of Delaware


It is becoming increasingly evident that multi-core chip architecture are emerging as a solution to efficiently amortizing the ever-growing number of transistors on a chip. However the success of such multi-core chips depends on the advances in system software technology, such as compiler and run-time system, in order for the application programs to exploit thread level parallelism out of originally single-threaded applications and to fully utilize the hardware on-chip concurrency.

In this paper, we propose a method which, from a parallel and non-parallel imperfect loop nest written in a standard sequential language such as C or Fortran, automatically generates a multi-threaded software-pipelined schedule for multi-core architectures. The generated schedule already contains all the necessary synchronization instructions and is guaranteed free of deadlocks and buffer overflow. The feasibility of the proposed method within a modern compiler infrastructure has been verified through a pilot implementation in the Open64 compiler and tested on the IBM Cyclops multi-core architecture. Experimental results show that the performance exhibits good scalability even with 100 cores. Our light-weight synchronization mechanism minimizes the dependencies stalls and synchronization overheads without the use of dedicated hardware support.