Intel Working On Energy Aware Scheduling For x86 Hybrid CPUs

For a number of years Arm CPUs on the mainline Linux kernel have supported Energy Aware Scheduling (EAS) as a means of providing the kernel's scheduler with the information to influence its scheduling decisions based on the estimated energy consumed by the CPU cores. EAS employs an energy model for helping to place tasks between the big.LITTLE cores for optimal energy efficiency and a minimal impact on throughput. Intel has been working to eventually support Energy Aware Scheduling on their x86 hybrid CPUs too.

As shown in yesterday's Core i9 12900K benchmarks on Linux 6.0, the Linux support/performance for hybrid processor designs like Alder Lake have come a long way over the past year with many improvements. There is still more on the way though with the recently cited "classes of tasks" for hybrid CPUs and proper Thread Director integration. Another element being worked on by Intel is Energy Aware Scheduling support.

Len Brown and Ricardo Neri, both of Intel, presented at the Linux Plumbers Conference this week around Linux scheduling on Intel hybrid architecture hardware. EAS in current form isn't a great match to Intel's processor design but at least Intel has the engineering resources and talent to change that for the upstream open-source kernel.

Given the original Arm focus, EAS doesn't currently take into account SMT/HT nor turbo frequencies / boost nor hardware P-states. There can also be the matter at least with Alder Lake where the P-cores can be "often" more efficient than the E-cores.

Those wanting to learn more about the work toward Energy Aware Scheduling for Intel CPUs can see the Intel LPC Dublin 2022 presentation embedded below. There is also the slide deck (PDF).