Von Neumann model

The von Neumann model was an “efficient bridge between software and hardware” because:

  • Hardware designers could build chips to execute it efficiently.
  • Software developers could write high-level programs that compile into this model.

Thus, the von Neumann model is the connecting bridge that enables programs from the diverse and chaotic world of software to run efficientby on machines from the diverse and chaotic world of hardware.

Bulk-synchronous parallel (BSP) model

it is a viable candidate for the role of bridging model.

Valiant wants parallel simulations to be almost as fast as ideal ones.

  • The extra cost should be only a small constant factor, not growing with processor count.
  • He tries to avoid efficiency loss that scales with log(p).
  • The model should work well for any number of processors, from a few to millions.

Features of BSP model

A major feature of the BSP model is that it provides this option with optimal efficiency (i.e., within constant factors) provided the programmer writes programs with sufficient parallel slackness.

BSP can automatically manage communication and memory efficiently if the program exposes

enough parallel work. If there’s enough parallelism (many tasks per processor), the model achieves near-optimal performance with little manual tuning.