While Intel has been making steady progress around [1]enhancing the Linux kernel handling for CPUs with a mix of P and E cores for proper task placement and power optimizations, one area that still is less than desirable for these hybrid Intel Core processors is around virtualization. But Intel engineers are now actively working on improving the Linux virtualization infrastructure for being able to convey the P/E core differences among vCPUs so that the guest VMs can better behave in such environments.

Intel engineers Zhao Liu and Zhenyu Wang presented at the KVM Forum 2024 in Brno, Czech Republic on Monday around their CPU virtualization enhancements for Intel hybrid platforms. The Intel work is to ultimately overcome QEMU/KVM currently being unable to expose P-core / E-core differences to VMs for better task placement and other core differences among vCPUs.

The Intel engineers are working on a QEMU API to allow creating hybrid CPU / cache topologies for guests, ensuring VMs under QEMU can properly enumerate the core differences, and VM optimizations around hybrid CPUs such as being able to leverage Intel Thread Director and Turbo Boost Max Technology.

With the work by Intel they are seeing up to a 14% improvement in the performance of Windows virtual machines.

They are seeing other healthy improvements as well, including for Linux guest VMs.

Those interested in the work being pursued by Intel to enhance virtualization for hybrid Core CPUs can learn more via [2]the PDF slide deck from their KVM Forum 2024 presentation.



[1] https://www.phoronix.com/news/Linux-6.12-Hybrid-No-SMT-Cap

[2] https://pretalx.com/media/kvm-forum-2024/submissions/NYWTMH/resources/The_Road_to_Optimal_CPU_Virtualization_on_Hy_nC2wAWI.pdf