While it is in most cases sufficient to let the hypervisor control processor performance states (e.g., HWP) for performance reasons, it may still be beneficial to guest OSes (Linux only) to have virtual HWP to guide its scheduling. A typical use case is that the highest performance level, when being different on different cores, gives guest OSes a hint on which processors they should schedule single-threaded workloads. This was originally for SoCs with the same core type but different highest level due to manufacturing reasons but is now more useful to VMs with both P-cores and E-cores.
ACRN hypervisor shall be configurably able to provide virtual HWP to any VM.
izhouwu
commented
1 year ago
While it is in most cases sufficient to let the hypervisor control processor performance states (e.g., HWP) for performance reasons, it may still be beneficial to guest OSes (Linux only) to have virtual HWP to guide its scheduling. A typical use case is that the highest performance level, when being different on different cores, gives guest OSes a hint on which processors they should schedule single-threaded workloads. This was originally for SoCs with the same core type but different highest level due to manufacturing reasons but is now more useful to VMs with both P-cores and E-cores.
ACRN hypervisor shall be configurably able to provide virtual HWP to any VM.