Write propagation: Writes all become visible to other processors eventually.

Relaxed consistence Reads can move in front of its ownwrite,

Total store ordering (TSO): P can read B reads by other processors cannot return new value of A until the write to A is observed by all processors.

• if P1 writes A <- 1, P2 cannot read A == 1 before P3 can also read A == 1.

PC: Can Return thevalue of any writebefore ht write isobserved by all processors.

Cache coherence:

• Singlememory location
• Program Order FOR EACH MEMORY LOCATION
• Write propagation FOR EACH MEMORY LOCATION
• Write serialization FOR EACH MEMORY LOCATION

Memory consistency:

• All different memory locations

Relaxed memory consistency:

• Allowed read or write ordering for a single memory location.
• STILL PRESERVES CACHE COHERENCE FOR EACH MEMORY LOCATION

Processor Consistency is cache coherent!

• WRite serialization: TOTAL ORDER for writes for that memory location
• This means that if the writes come from the sameprocessor, these writes will be seen in order
• But if they come from ddifferent processors, they may not be seen in order.

PSO:

• Preserves store order,
• Only diff between this and TSO is it allows W->W reorderings