Intel’s Hybrid Big Core Little Core strategy could be a disaster for Alder Lake suggests leak

Intel’s Alder Lake Core is set to bring the design principles of Lakefield to desktop platforms, offering users hybrid processors with both big cores and little cores. The powerful big cores will provide performance where it is necessary, and the smaller cores will deliver higher performance/watt and supplement the performance of their stronger counterparts in multi-threaded workloads.  

With Alder Lake, Intel is reportedly offering consumers processors with eight big cores and eight little cores, offering users sixteen total cores and the potential for a lot of hardware/software headaches. Before we get into this, let’s discuss the advantages of Intel’s hybrid core designs. 

The advantages

In some areas of the PC market, power consumption is everything, especially within the mobile section of the PC space. Hybrid core designs allow high-efficiency “small cores” to be combined with more powerful “big cores” to enable increased performance/watt characteristics. At idle, the small cores can handle most workloads. When more performance is required, the processor’s big cores can jump into action, creating a highly responsive PC while also offering users a longer battery life. 

Another advantage is that the so-called “small cores” are smaller than their more performant counterparts. These cores will take up less die space than their larger counterparts, allowing Intel to increase their core counts without huge die space costs. That said, this is also a disadvantage for Intel, as we will discuss below. 

The Disadvantages

We already know with Lakefield that Intel’s hybrid processer have their flaws. With Lakefield, we know that Intel’s high-performance Sunny Cove CPU cores lack support for AVX-512 and hyperthreading, cutting down Sunny Cove’s feature set to match the low-power Tremont cores that they are paired with. 

While Intel’s big cores and little cores share the same ISA, that doesn’t mean that both sets of cores share the same feature set, and this isn’t due to change with Alder Lake. 

Based on a slide from JZWSVIC over on the zhihu website (see below image), as uncovered through @9550pro on Twitter, we can see that Alder Lake’s big CPU cores will lack AVX-512, Intel TSX-NI and FP16 support when the processor’s little cores are enabled. 

This strange design quirk will force Intel users to deactivate their small CPU cores to enable support for these hardware features, horribly fragmenting their hardware ecosystem. Intel’s lack of support for AVX-512 in the consumer space is already a major sticking point for the company, and it looks like this is set to continue well into the future. 

Right now, AVX-512 is available on Intel’s Ice Lake mobile processors and the company Skylake-X and Cascade Lake-X series of processors. As of now, no mainstream desktop processors from Intel support AVX-512, preventing any kind of widespread adoption for the feature.