RPCS3 Developer Claims AVX-512 Is Power-Efficient, Blames Skylake-X For Its Poor Reputation
Yesterday, developer of PS3 emulator RPCS3 Whatcookie posted a 20-minute YouTube video to their YouTube channel in defense of AVX-512, a maligned CPU instruction set that debuted with Intel's Skylake-X architecture in 2015 and didn't see adoption by AMD CPUs until 2022's Zen 4. Specifically, Whatcookie debunks claims that modern implementations of AVX-512 are inefficient by showcasing benchmarks of both RPCS3 and other pieces of software using AVX-512 on modern CPU architectures, showing that the instruction set still manages higher performance at the same wattage levels, the same performance at lower wattage levels, and much higher performance at slightly-higher wattage levels.
Whatcookie doesn't stop there, though. He also includes a mini history lesson on the instruction set in his 20-minute video, highlighting how the initial Skylake-X implementation actually did substantially lower clock speeds and boost power draw when AVX-512 was in use. These issues were mitigated on Intel's high-end server-grade Xeon CPUs, and were seemingly artificially exaggerated on consumer-grade Skylake-X chips thanks to more severe downclocking enforced in firmware.
All this isn't to say that AVX-512 is a perfect CPU instruction set, by any means. On modern architectures from Intel and AMD, some minor downclocking is still present when executing enough full-length AVX-512 instructions at once, but these are enforced by more typical thermal and power constraints, not firmware constraints as with consumer Skylake-X chips. This means that AVX-512 still shows much higher performance and efficiency were in use on modern CPUs compared to AVX2, and this discrepancy has already been highlighted by benchmarks from several sources including Phoronix and VideoLAN, not just RPCS3 development.
To those who have been keeping track of RPCS3 development or AVX-512 adoption in recent years, this actually shouldn't be that surprising. Back in 2022, we covered performance gains of up to 30% on RPCS3 when using AVX-512 ourselves, and just last month we reported on Phoronix's benchmarks showing major performance benefits of AVX-512 on the AMD Ryzen 9 9950X.
Sadly, while modern benchmarks on modern hardware should seemingly have cleared AVX-512's name by now, popular consensus of the AVX-512 instruction set still points to a maligned reception tainted by Intel Skylake-X all these years later. Perhaps that shouldn't be surprising, though, considering how long Intel iterated upon Skylake's 12nm architecture before finally adopting an all-new 10nm architecture with Alder Lake in 2021— an architecture that outright disabled AVX-512 because the new E-cores couldn't support it, although P-cores could.
Thankfully, AVX-512 seems to be a straightforward power and performance win on modern CPU architectures from Intel and AMD alike, despite how poorly it fared with Skylake-X's launch. That bitter aftertaste will linger for some time, though— and as Whatcookie highlights in a concluding skit, even the likes of the supposedly PhD-level GPT-5 still uncritically repeats critique of Skylake-X-distorted AVX-512 performance as gospel.
Image Credit: Der8auer for Skylake-X delidded thumbnail, Whatcookie for RPCS3 benchmark images
