The PS3 Licked the Many Cookie

Summary

The PS3 Licked the Many Cookie This post is inspired by I want a good parallel computer It is important to understand why the PS3 failed. The perspective here was juniorish dev working on simulation and rendering in triple-A. I remember less than I knew and knew less than most! However, what I can provide here is the hindsight of someone who actually developed and shipped titles 1 on the PS3. I wanted the PS3 to succeed. To be more specific; I wanted Many-Core to succeed. The PS3 failed developers because it was an excessively heterogenous computer; and low level heterogeneous compute resists composability.2 More like Multicore than Many The primary characteristic of Many-Core is, by virtue of the name, the high core count. Many-core is simply a tradeoff that enables wide parallelism through more explicit (programmer) control. CPU GPU Many Few Complex Cores Wide SIMD Many Simpler Cores Low latency, OOO, SuperScalar vector instruction pipe, High latency RISC-like, scalar Cached and Coherency Protocol Fences, flushes, incoherence Message passing, local storage, DMA Explicit coarse synchronization Implicit scheduling Explicit fine synchronization At first glance, the SPEs of the PS3 fit the bill. They seem to have all the characteristics of Many-Core. The problem is that most important characteristic, that there is many cores, is significantly lacking. First off you didnt get the full 8 SPEs as a (game) developer. Out of the 8 SPEs one was disabled due to die yield and the OS got a core and a half. While this changed with updates one only really got 5-6 SPEs to work with. The Xbox360 in contrast had what amounted to 3 PPEs (2 more). So the Cell really featured at most 3 more (difficult to use) cores than the Xbox360. Computationally Weak Components The claim from wiki is a single SPE has 25 GFlops and the PS3 GPU has 192 GFlops. If you absolutely maxed out your SPE usage you would still not even be close to the power of the underpowered PS3 GPU. For contrast the Xbox36...