Question: Behavior of L2 on eviction when an L1.5 owner silently modifies data in E state #174
Description
Hi, I have a question about the expected coherence behavior in the following scenario:
A core holds a cache line in the Exclusive (E) state. While in E, the core can silently modify its data without informing L2 (because E → M is a silent transition according to the micro arch).
My question is:
1- If the owner silently modified the line while in E, what behavior should we expect from the L2 cache when the line is later evicted from L2?
2- How and when will the modified data be written back to memory in case of eviction if the core never explicitly sends any write-back until eviction?