Strict Consistency

The most stringent consistency model is called strict consistency. It is defined by the following condition:

Any read to a memory location X returns the value stored by the most recent write operation to X.

This definition implicitly assumes the existence of absolute global time so that the determination of "most recent" is unambiguous. Uniprocessors have traditionally observed strict consistency.

In summary, when memory is strictly consistent, all writes are instantaneously visible to all processes and an absolute global time order is maintained. If a memory location is changed, all subsequent reads from that location see the new value, no matter how soon after the change the reads are done and no matter which processes are doing the reading and where they are located. Similarly, if a read is done, it gets the then current value, no matter how quickly the next write is done. 

                
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