Write Hit Policies:
o Update next level on every write
o Cache is always clean
o A lots of traffic to next level (mostly write)
o Write to cache and mark block dirty
o Update primary memory to eviction
o Less traffic to next ,but more complicated eviction and coherence
o Reads use directly and data array at the same time
o Write use directory first then data array
o How to we pipeline to permit one read or write per cycle?