Disabling Zen 5’s Op Cache and Exploring its Clustered Decoder
Zen 5 has an interesting frontend setup with a pair of fetch and decode clusters. Each cluster serves one of the core’s two SMT threads. That creates parallels to AMD’s Steamroller architecture from the pre-Zen days. Zen 5 and Steamroller can both decode up to eight instructions per cycle with two threads active, or up to four per cycle for a single thread.Despite these decoder layout similarities, Zen 5’s frontend operates nothing like Steamroller. That’s because Zen 5 mostly feeds itself off a...
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