Strict Persistency
In strict persistency model, the order stores are persisted is the same as the order they became visible to all cpus. Therefore, whenever a crash happens, the non-volatile state is consistent w.r.t. the memory consistency model.
Strict persistency alone does not guarantee Crash Consistency, as it only prevents reordering.
Implementation
A naive way of implementing strict persistency on weak persistency model is to insert a flush operation after every store after every memory access. However, this will introduce redundant flushes.
Only inserting flushes after stores are not sufficient when there are multiple threads. See the example below from PSan paper.
