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Historically the only reason Intel has won on absolute top performance gaming FPS is because their raw single-threaded performance has beaten AMD due to most ga
by devonkim 7y ago
Historically the only reason Intel has won on absolute top performance gaming FPS is because their raw single-threaded performance has beaten AMD due to most games still being bad / ineffective with multiple threads. For the first time in many processor generations this may actually not be true because of Intel’s stumble in their 10 nm transition.
- smileybarry 7y agoThat changed slightly with Ryzen: AMD closed the gap on single-threaded IPC (close enough, anyway) but the new issue with Zen 1 and Zen+ was memory/cache/inter-CCX latencies. Zen+ solved most of the memory latency issues but hadn't fixed cache/CCX latencies much. Supposedly Zen 2 solved most of that. (And some game benchmarks like CSGO suggest they really did) We'll see how it actually pans out since there's still the issue of inter-CCX latency (and now even cross-chiplet latency).
- mizzack 7y agoWindows 10 1903 has scheduler changes (intra CCX bias?) that seem to offer significant performance uplift in games (10+%)
- smileybarry 7y agoIt doesn't solve all of it however. If your program has more than "$number_of_cores / 2" threads, you'll cross the CCX boundary at some point(s). On Zen 2, that instead changes to "$number_of_cores / 4" (CCX boundary) or "$number_of_cores / 2" (chiplet boundary). Inter-CCX communication requires hopping over the Infinity Fabric bus, which (in case of Zen 1, no newer benchmarks) increases thread latency from ~45us to ~131us. I'm sure it was reduced in Zen+ and is probably closer to 100us by now. However, I'm not sure if inter-chiplet communication will be the same (e.g.: has its own IF bus) or worse (IO chip overhead). Hopefully someone runs the same inter-thread communication benchmarks on Zen 2.