Operating Systems: Concurrent and Distributed Software Design

9.8. Definition of single concurrent actions

We now attempt to define a 'single' action that might be carried out by a process. As stated in the introduction to Part II, such a definition must be somewhat arbitrary and is made in order to divide the material to be presented so that we can focus on it in a coherent order. We could define a single action to be a single read of main memory or a single write to main memory. There is no problem arising from such operations being carried out by concurrent processes, since each operation is guaranteed by the hardware to be indivisible or atomic. This definition of a single operation would not help us to focus on the problems.

Rather, we are concerned with a higher-level or logical operation which involves ...