Quantifying the benefits of SPECint distant parallelism in simultaneous multithreading architectures

Abstract

We exploit the existence of distant parallelism that future compilers could detect and characterise its performance under simultaneous multithreading architectures. By distant parallelism we mean parallelism that cannot be captured by the processor instruction window and that can produce threads suitable for parallel execution in a multithreaded processor. We show that distant parallelism can make feasible wider issue processors by providing more instructions from the distant threads, thus better exploiting the resources from the processor in the case of speeding up single integer applications. We also investigate the necessity of out-of-order processors in the presence of multiple threads of the same program. It is important to notice at this point that the benefits described are totally orthogonal to any other architectural techniques targeting a single thread.