title: Cache eviction from L1 cache on L2 eviction
body: <p>I have a basic question about the policy followed by the memory system. </p>
  
  <p>Consider a core with private L1 and L2 caches. After L2 cache we have a bus on which the coherence traffic runs. Now, if a cache line for address(X) is evicted from the L2 cache, is it necessary to evict that address from the L1 cache ??</p>
  
  <p>The reason for eviction can be that it helps in maintaining the invariant of the coherence protocol [if a line in l2 shows invalid this core does not contain this address].</p>