Do we want to change cpu_idle_init to return failure right away
when Deep C-States are not supported? cpu_idle_init can check
cpu_deep_cstates_supported().
Currently cpudrv queries ACPI for C-State info even when
idle_cpu_no_deep_c is set. I think this is leftover from before
we had the cpu_deep_idle tunable.
Here is a proposal for variable/keyword semantics:
idle_cpu_no_deep_c:
Disables ACPI query for C-State information. Disables C-states.
Kernel will not report valid C-state information in kstat(s).
Usage: only used to workaround a bug in ACPI, hardware, or software.
cpu_deep_idle:
Do not use C-States for performance reasons.
Kernel can query ACPI. Kernel will still report available C-State
information in various kstat(s).
Usage: disable C-States solely for performance reasons.
Does this sound good?
Regards,
Bill
