Weak Consistency
Synchronization is used to update data.
Characteristics:
- Access to SYNCHRONIZATION variables are sequentially consistent
- No access to a synchronization variable is allowed to be performed until all previous writes have completed everywhere
- No data access (R or W) is allowed to be performed until all previous accesses to synchronization variables have been performed
Intended for applications not needing to see all writes, or not needing to see them in order
But can not distinguish between entry and exit to a critical region and therefore is expensive
- Need to know whether we are about to start reading shared variables
- …or have finished writing them