Intel Submits Linux Scheduler Patches to Fix Hybrid CPU Load Balancing

Intel engineers have submitted a set of optimization patches for the Linux kernel scheduler, planned for formal inclusion in the Linux 7.3 merge window. The patches aim to improve load balancing on modern Intel Core and Core Ultra hybrid processors, addressing a long-standing defect in core cluster scheduling code when high-performance large cores and energy-efficient small cores are arranged in a mixed configuration.

In 2021, the Linux kernel introduced cluster-aware scheduling to optimize task distribution among core clusters sharing L2 cache or other mid-level resources. However, the mechanism was initially designed for uniform systems with balanced core capabilities, and under asymmetric compute topologies it leads to imbalanced task allocation among small-core clusters. This issue has affected multiple processor generations including Alder Lake, Lunar Lake and future Panther Lake.

Intel kernel engineer Ricardo Neri's patches fix the cluster-level load balancing logic under asymmetric architectures. The patches have entered the sched/core branch of tip/tip. git and are planned for official release with Linux 7.3.