On Thu, Aug 14, 2014 at 03:57:07PM -0400, Ashwin Chaugule wrote:

What is CPPC:

CPPC is the new interface for CPU performance control between the OS and the platform defined in ACPI 5.0+. The interface is built on an abstract representation of CPU performance rather than raw frequency. Basic operation consists of:

Why do we want this? Typically we've ignored ACPI and gone straight to MSR access, intel_pstate and intel_idle were created especially to avoid ACPI, so why return to it.

Also, the whole interface sounds like trainwreck (one would not expect anything else from ACPI).

So _why_?