> A barrier instruction forces all memory operations before it to complete before any memory operation after it can begin. That is, a barrier instruction effectively reinstates sequential consistency at a particular point in program execution.

> Of course, this is exactly the behavior we were trying to avoid by introducing store buffers and other optimizations. Barriers are an escape hatch to be used sparingly: they can cost hundreds of cycles.

I may be wrong, but I think to readers who do not already know what barriers do and are, this makes barriers seem like blocking behaviours.