moe-cache : LRFU/MQ-like hybrid cache, ClassLRU (#31233)
* moe-cache : LRFU/MQ-inspired hybrid cache
* make the clock advance by N tokens: use the real token count (ne[1] is always 1, ids have n_expert_used entries per token)
* sel is a RESHAPE node, the orig input is in src[0], so sel->src[0]->ne[1] is the count
* c for the class index, last_use for last use time
* explain the roles of these
* compute the key once
* use the key directly instead of re-reading
* show how the score is computed from the age
* remove the branch and clarify exp2 and log2 relationship
* reword the header comment and elaborate on unused slots and sorting
* not a copy, not just skip
* std::array maybe
* Revert "std::array maybe"
This reverts commit 7649b1f172db4941a854ad115bec0c7e062b65b9.
* half life it is
* add key and iteration helpers
* extract decayed_crf
* bump classes to 8, document the formula, display the cache size in token worth count
* assert the computed number of classes matches the half life
