by Steve Leibson
Edward Richards, a Senior Field Applications Engineer for Green Hills Software, had a confession to make at the Real Time Embedded Computing Conference (RTECC) held in Santa Clara recently. No matter the processor architecture in use, he had no more single-core customers in Silicon Valley. All of his clients had moved to multicore platforms. Now even though Richards’ world doesn’t encompass the entirety of the embedded-design space, that’s a pretty big admission and it represents a huge change in the way embedded systems are developed.

Richards says he has seen wholesale adoption of multicore processor architectures because they provide embedded developers with better net results. That’s not a surprising observation these days because we hit the ceiling on rising processor clock rates and falling DRAM access times years ago. However, some things do not change. Operating systems still need to be reliable and deterministic he says, even when working with multiple processor cores.

Multiprocessor-style and multithreaded coding are now widespread according to Richards, highlighting needed differences in coding styles including real versus virtual concurrency, determinism, and dealing with inter-core overhead (spin locks). It’s not unusual for Richards to see no net performance improvement in code blindly moved to multicore architectures. Spin locks sometimes soak up all of the extra processor cycles after a port. Richards has seen situations where two processor cores deliver anywhere from 0.9x to 1.99x the performance of one core, depending on how the multicore software was written. “If you can’t visualize the parallelism,” he says, “you can’t move forward.”

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