Dealing with memory access ordering in complex embedded designs

Chris Shore, ARM
embedded.com (December 10, 2014)

Things used to be so simple in the embedded world. For most of us, the systems for which we develop these days are orders of magnitude more complex than the ones we were using even five years ago.

As embedded systems chase ever higher performance, processor designers reach deeper and deeper into the toolbox for microarchitectural innovations. Many of these, mercifully, are transparent to the programmer. The challenge for us is that many are not transparent; we to be aware of what is going on and write our software in different ways. In some cases, we are missing out on improved performance, but in many cases, existing software techniques simply won’t work properly unless we take into account some of the new ways in which modern embedded systems function.

The area I address in this article is memory accesses, specifically the order in which they happen. The simple act of loading, storing, and transferring data between processor and memory is much more complex than it used to be.

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