Analyzing Lion Cove's Memory Subsystem in Arrow Lake

A CPU core can perform very differently depending on the platform it's deployed in. That was on full display with Skymont's wildly different performance characteristics in Lunar Lake and Arrow Lake. We've already covered Intel's latest P-Core architecture, Lion Cove, in Lunar Lake. Now, it's time to check it out in Arrow Lake, where it sits on a much higher performance platform.

Arrow Lake's higher power budget lets the Core Ultra 9 285K run its P-Cores at 5.7 GHz, rather than 4.8 GHz in the Core Ultra 7 258V. A higher area budget lets Arrow Lake feed those P-Cores with 36 MB of L3 cache, up from 12 MB in Lunar Lake. Cache capacity increases extend to the core too, with each Arrow Lake P-Core getting 3 MB of L2. It's a slight boost over Lunar Lake's 2.5 MB. Finally, Arrow Lake improves DRAM access latency.

All that means Lion Cove is faster and better fed in Arrow Lake than it was in Lunar Lake. In SPEC CPU2017, that translates to 24.8% and 23.4% gains in the integer and floating point suites, respectively. That’s greater than a typical performance gain between CPU generations. However, it stops short of being over a 50% performance difference like with Skymont. That’s mostly down to Skymont getting the short end of the stick in Lunar Lake, where it had no L3 cache and suffered from high L2 miss latency. Lunar Lake made a decent effort to feed its P-Cores, and actually enjoys lower L3 latency. Arrow Lake’s memory subsystem is better overall, but its advantage for Lion Cove is less extreme than with Skymont.

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