On 27 March 2015 at 12:02, Shilpasri G Bhat <shilpa.b...@linux.vnet.ibm.com> wrote: > The power and thermal safety of the system is taken care by an > On-Chip-Controller (OCC) which is real-time subsystem embedded within the > POWER8 > processor. OCC continuously monitors the memory and core temperature, the > total > system power, state of power supply and fan. > > The cpu frequency can be throttled for the following reason: > 1)If a processor crosses its power and temperature limit then OCC will lower > its > Pmax to reduce the frequency and voltage. > 2)If OCC crashes then the system is forced to Psafe frequency. > 3)If OCC fails to recover then the kernel is not allowed to do any further > frequency changes and the chip will remain in Psafe. > > The user can see a drop in performance when frequency is throttled and is > unaware of throttling. So we want to report such a condition so that user can > check the OCC status to reboot the system or check for power supply or fan > failures.
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