An anonymous reader writes: Intel is returning to in-order cores after two decades with Atom and Knights. ARM is already building in-order cores for iPhones, iPads, and Androids. IBM has switched to in-order cores after building generations of out-of-order cores. This indicates a clear trend that in-order cores are back in the mainstream. Highlighting the performance characteristics of in-order and out-of-order cores, Dr. Aater Suleman's article explains why programming for in-order cores is very different from programming for the now-traditional out-of-order cores. Thus, this new trend requires a change in compilers, tools, and programming techniques. Compilers need to get better at removing useless code and instruction scheduling. Programmers need to weigh new trade-offs and perform classic optimizations that have been forgotten. I liked this article particularly for the very simple code examples and a simple explanation of in-order and out-of-order differences. The message is clear: programmers and compilers need to understand in-order cores and target their code better.
