Intel is planning to offer a version of its hybrid Alder Lake chip—without efficiency cores—and AVX512 is indeed dead on 12th gen.
The company confirmed with PCWorld that AVX512 would not be present in its upcoming 12th-gen chips, which now moves the controversial instruction set back into the dead column—cue your Monty Python memes.
A gaming software developer guide that Intel published last week indicated that AVX512 would be in Alder Lake. This differed from the company’s previous statements that the feature—while present in the actual cores—would be permanently turned off so as not to confuse operating systems.
Company officials had said that AVX512 was in the Alder Lake performance (P) cores but not in its efficiency (E) cores, so to present a uniform face to the OS, the company was fusing off the feature to remove it permanently. The subsequent gaming guide, however, said that AVX512 would be present if the E-cores were turned off on a system. The developer’s guide has since been removed while being updated.
News of the Intel offering its hybrid Alder Lake chip in a non-hybrid version looks to be holding though.
“Mobile SKUs will feature up to 6 P-cores and 8 E-cores. All mobile SKUs will include E-cores. Desktop SKUs will feature up to 8 P-cores and up to 8 E-cores. Specific desktop SKUs will feature only P-cores,” the guide said.
It’s also a little clearer to us that the P-core only version is likely to be offered in lower-end versions. We had speculated that the P-core only version could potentially be a high-performance version, but with only six P-cores and no E-cores, it’s likely more of a lower-performance chip.
The temporarily removed guide was aimed at game developers and gives examples of where developers would want to take advantage of the E-cores and the P-cores. Part of that advice is for developers to write games that don’t try to hammer all available cores in a CPU just because those cores are there.
“Testing has revealed that some legacy software can show a performance inversion as you increase core counts,” the software guide says. “This is not an issue specific to Alder Lake, but more of a scalability challenge. As the number of threads increases, so does the overhead of managing them.”
“If there isn’t enough work for the threading system, the overheads can become greater than any benefit derived from increased work distribution. Developers shouldn’t naively scale to the available core count on the system, but instead scale to the point where benefits decrease below a threshold decided by the programmer. This allows the OS more opportunities to manage hardware resources, parking unused cores and diverting power to the parts of the system that need it, potentially increasing frequency.”
Some will say this is Intel telegraphing a weakness of its new hybrid design, but the paper does shed a little more light on how Alder Lake will perform in gaming.
“Analysis of games on hybrid architectures has shown the majority of games perform well, with older, or less demanding, games favoring the Performance cores. Games that were already built to heavily utilize multithreading, and that can scale to double-digit core counts, were found to benefit from hybrid architecture due to better throughput. However, there are inevitable performance inversions, attributed to either poor multithreading game architectures, poor OS scheduling, or increased threading overhead.”
The guide recommends that developers basically keep their libraries and development tools updated to get the best out of Alder Lake.
Intel said that for titles where there is no optimization, its Intel Thread Director will try to dispatch work to the proper P-core or E-core accordingly. But the guide also admits there can be times when tasks aren’t assigned to the right core.
What does this all mean? We’re probably in for some surprises when Alder Lake is released with some games screaming and some leaving us with head-scratching results.