Editing Consistency model (section)

=== Slow consistency ===
[[File:Slow memory.gif|thumb|Slow memory]]

In slow consistency,<ref name="unified"/> if a process reads a value previously written to a memory location, it cannot subsequently read any earlier value from that location. Writes performed by a process are immediately visible to that process. Slow consistency is a weaker model than PRAM and cache consistency.

'''Example:'''
Slow memory diagram depicts a slow consistency example. The first process writes 1 to the memory location X and then it writes 1 to the memory location Y. The second process reads 1 from Y and it then reads 0 from X even though X was written before Y.

Hutto, Phillip W., and Mustaque Ahamad (1990)<ref name="slow">{{cite book
|author1=Hutto, Phillip W. |author2=Mustaque Ahamad
|title=Proceedings.,10th International Conference on Distributed Computing Systems
|chapter=Slow memory: Weakening consistency to enhance concurrency in distributed shared memories
|    date = 1990
| publisher = IEEE 
|   pages = 302–309
|     doi = 10.1109/ICDCS.1990.89297
|    isbn = 978-0-8186-2048-5
|s2cid=798676
}}</ref> illustrate that by appropriate programming, slow memory (consistency) can be expressive and efficient. They mention that slow memory has two valuable properties; locality and supporting reduction from atomic memory. They propose two algorithms to present the expressiveness of slow memory.