When we evict a block from L1 and move it to L2 there is a brief window of
time where we have removed the block from the L1 map and yet the victim
handler has not completed execution. Some read-your-write use cases can be
significantly impacted even though the window is small.
Victim handling can be made atomic with respect to the unmapping operation.
The upside is there will be no L1+L2 misses during the transition. The
downside is if the victim handler takes a long time to execute – currently
they are all very fast, so only a theoretical risk – then other removals or
insertions in L1 can block until it completes.
Signed-off-by: Duo Zhang <zhangduo@apache.org>
Signed-off-by: Viraj Jasani <vjasani@apache.org>
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