|The biggest conceptual difference between sequential and multithreaded programs is the way the programmer should view memory. In a sequential program, memory can be thought of as being stable unless the program is actively modifying it. For a multithreaded program, however, it is better to think of all memory as spinning (being changed by other threads) unless the programmer does something explicit to freeze (or stabilize) it.|
Sequential consistency is an intuitive model and, as the previous example shows, some of the concepts of sequential programs can be applied to it. It is also the model that gets implemented naturally on single-processor machines so, frankly, it is the only memory model most programmers have practical experience with. Unfortunately, for a true multiprocessor machine, this model is too restrictive to be implemented efficiently by memory hardware, and no commercial multiprocessor machines conform to it.
Jestem w połowie czytania, strasznie długo to trwa, ale naprawdę warto.