2 ms·
The only 9-per cycle I could find was skymont(e-core), which is really 3x3-wide clusters. Lion cove (p-core) claims 8-wide (unclear if sequential or multiple cl
by MobiusHorizons 2y ago
The only 9-per cycle I could find was skymont(e-core), which is really 3x3-wide clusters. Lion cove (p-core) claims 8-wide (unclear if sequential or multiple clusters), and zen 5 is 2x4-wide. In contrast M1 had a true 8-wide decoder and M4 has a 10-wide decoder.
My understanding is that on x86 the complexity increases super linearly with decode width because of variable length instructions, while on fixed width architectures (or even a couple of sizes like arm thumb or risc-v compressed) it’s basically linear complexity.
This chips and cheese article seems to back this up.
https://open.substack.com/pub/chipsandcheese/p/zen-5s-2-ahead-branch-predictor-unit-how-30-year-old-idea-allows-for-new-tricks?selection=862f836c-63cb-41d5-a804-53a36b209e25&utm_campaign=post-share-selection&utm_medium=web https://open.substack.com/pub/chipsandcheese/p/zen-5s-2-ahea...