> Yes, I also think the cache structure modeled by ruby is quite confusing
> at
> first.
> In addition to a shared controller, the L1 & L2 are exclusive rather than
> inclusive.
> It's quite strange to me. Sorry for my ignorant.
> One more question, why did you say that CMP don't need fast path?
The CMP protocols have separate L1 and L2 controllers. If you disable fast
path, the L1 controller sees every hit but there is still a distinction
between L1 and L2 hits (because the controllers are separate). For one,
this allows more flexibility in doing actions on hits (like setting bits).
This also allows an arbitrary L1 hit latency to be used by setting the
SEQUENCER_TO_CONTROLLER latency to whatever you want. And the L1 hits show
up in the transition counts in the Ruby stats file.
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