 Sequential consistency

Execution behaves as if steps occurred in one total order preserving each participant's program order; reads observe the latest preceding writes in that order. This is the definition given in the 1979 paper How to Make a Multiprocessor Computer That Correctly Executes Multiprocess Programs, printed p. 690. It permits many thread interleavings, including the lost update under mutual exclusion; ordering individual accesses does not combine them into one atomic operation.