Translating submachine locality into locality of reference

In this work, we show that the submachine locality exposed by hierarchical bulk-synchronous computations can be efficiently turned into locality of reference on arbitrarily deep hierarchies. Specifically, we develop efficient schemes to simulate parallel programs written for the Decomposable BSP (a BSP variant which features a hierarchical decomposition into submachines) on the sequential Hierarchical Memory Model (HMM), which rewards the exploitation of temporal locality, and on its extension with block transfer, the BT model, which also rewards the exploitation of spatial locality. The simulations yield good hierarchy-conscious sequential algorithms from parallel ones, and provide evidence of the strict relation between submachine locality in parallel computation and locality of reference in the hierarchical memory setting. We also devise a generalization of the HMM result to the self-simulation of D-BSP augmented with hierarchical memory modules, which yields an interesting analog of Brent's lemma, thus proving that the enhanced model features a seamless integration of memory and network hierarchies

Translating submachine locality into locality of reference

In this work, we show that the submachine locality exposed by hierarchical bulksynchronous computations can be efficiently turned into locality of reference on arbitrarily deep hierarchies. Specifically, we develop efficient schemes to simulate parallel programs written for the Decomposable BSP (a BSP variant which features a hierarchical decomposition into submachines) on the sequential Hierarchical Memory Model (HMM), which rewards the exploitation of temporal locality, and on its extension with block transfer, the BT model, which also rewards the exploitation of spatial locality. The simulations yield good hierarchy-conscious sequential algorithms from parallel ones, and provide evidence of the strict relation between submachine locality in parallel computation and locality of reference in the hierarchical memory setting. We also devise a generalization of the HMM result to the self-simulation of D-BSP augmented with hierarchical memory modules, which yields an interesting analogue of Brent’s lemma, thus proving that the enhanced model features a seamless integration of memory and network hierarchies

Translating Submachine Locality into Locality of Reference

none3The design of algorithms exhibiting a high degree of temporal and spatial locality of reference is crucial to attain good performance on current and foreseeable computing systems featuring ever deeper memory hierarchies. Previous work has demonstrated that task parallelism can be efficiently transformed into locality of reference in two-level hierarchies. Recently, we moved a step forward and showed how the more structured type of parallelism exposed by submachine locality can be efficiently turned into temporal locality on arbitrarily deep hierarchies. In this work, we complete and extend the above result by encompassing also spatial locality. Specifically, we present a scheme to simulate parallel algorithms designed for the Decomposable BSP (a BSP variant which captures submachine locality) on the Hierarchical Memory Model with Block Transfer. The simulation yields good hierarchy-conscious sequential algorithms from parallel ones, and provides evidence of the strict relation between submachine locality in parallel computation and locality of reference (both temporal and spatial) in the hierarchical memory setting.Best Paper Award: Algorithms TrackmixedC. Fantozzi; A. Pietracaprina; G. PucciFantozzi, Carlo; Pietracaprina, ANDREA ALBERTO; Pucci, Geppin