Intel's Clear Linux Helping AMD EPYC Genoa Hit New Performance Heights

Written by Michael Larabel in Operating Systems on 27 December 2022. Page 1 of 4. 15 Comments

Similar to the great results of Intel's performance-optimized Clear Linux on the Ryzen 9 7950X, making use of Clear Linux on the new 4th Gen EPYC "Genoa" processors also helps in maximizing performance for these AVX-512 server processors. Here are some initial benchmarks.

While Intel optimizes their Clear Linux distribution for their own hardware, the extensively-tuned Linux distribution has long worked fine on AMD platforms going back years given the commonality of x86_64 and no arbitrary checks around Intel CPU presence. With the new AMD Ryzen and EPYC Zen 4 processors the use of Clear Linux is all the more interesting as it's one of the few Linux distributions supplying out-of-the-box optimizations around AVX-512 that are new on the AMD side with Zen 4.

Clear Linux in looking to maximize the performance on Xeon servers has for years offered AVX-512 tuned libraries that are loaded when installed on AVX-512-supported platforms. Thus now for Zen 4 processors is the potential for even better performance on the AMD side compared to the more conventional Linux distributions and their less aggressive performance optimizations.

Curiosity got the best of me over the holidays and so I fired up the latest Clear Linux rolling-release on the AMD Titanite server platform with dual EPYC 9654 96-core processors. Clear Linux installed without a hitch and then it was off to the benchmark races.

For this article the performance of Clear Linux is being compared to that of Ubuntu 22.10 as the newest Ubuntu Linux release (non-LTS for simply wanting the latest Ubuntu packages for the best performance there). Ubuntu 22.10 was tested both out-of-the-box with its default AMD P-State Schedutil configuration and then again when switching to AMD P-State with the "performance" governor active for one of the important performance changes particularly on server platforms. Clear Linux has long used the performance governor by default on desktop and server installations.

When running Clear Linux there was one noticeable issue encountered when running on this dual socket EPYC 9654 server: Clear Linux limits the number of supported CPU threads / logical cores to 320, rather than 384 threads seen with other Linux distributions given the two processors each with 96 cores / 192 threads. As for the 320 CPU thread limit I wasn't able to find out why it was set that way for Clear Linux besides the fact that Intel CPU configurations don't come close, but in any event only affects the top-end Genoa SKUs and even with that current limitation the Clear Linux performance still tended to be pretty wild in relation to more conservative distributions. [Update: Clear Linux has a change pending now to increase this 320 thread limit that will go into their updates shortly.]

While today's holiday benchmarking is just looking at Clear Linux against Ubuntu, I do have a larger Linux distribution performance comparison coming out on the EPYC 9004 series hardware that should be wrapped up in early January.

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