On Mon, Jul 30, 2018 at 07:06:21AM -0700, Srinivas Pandruvada wrote: > On Mon, 2018-07-30 at 14:16 +0300, Eero Tamminen wrote: > > Questions: > > > > * Does currently kernel CPU freq management have any idea which IO > > devices share TDP with the CPU cores?
> No. The requests we do to hardware is just indication only (HW can > ignore it). The HW has a bias register to adjust and distribute power > among users. > We can have several other active device on servers beside CPU which > when runs need extra power. So the HW arbitrates power. That's not entirely accurate AFAIK. "No" is accurate for Intel, but the ARM people have their IPA thing (not a beer): https://developer.arm.com/open-source/intelligent-power-allocation drivers/thermal/power_allocator.c which IIUC interacts with their cpufreq driver to disallow certain OPP states. And note that I discourage intel_pstate active mode.
