NAME

       cpupower-set - Set processor power related kernel or hardware configurations

SYNOPSIS

       cpupower set [ -b VAL ]

DESCRIPTION

       cpupower  set   sets  kernel  configurations  or directly accesses hardware registers affecting processor
       power saving policies.

       Some options are platform wide, some affect single cores. By default values are applied on all cores. How
       to modify single core configurations is described in the cpupower(1) manpage in the --cpu option section.
       Whether an option affects the whole system or can be applied to individual  cores  is  described  in  the
       Options sections.

       Use cpupower info  to read out current settings and whether they are supported on the system at all.

Options

       --perf-bias, -b
           Sets  a  register  on  supported  Intel processore which allows software to convey its policy for the
           relative importance of performance versus energy savings to the  processor.

           The range of valid numbers is 0-15,  where  0  is  maximum  performance  and  15  is  maximum  energy
           efficiency.

           The  processor  uses  this  information in model-specific ways when it must select trade-offs between
           performance and energy efficiency.

           This policy hint does not supersede Processor Performance states (P-states) or CPU Idle power  states
           (C-states),  but  allows  software  to have influence where it would otherwise be unable to express a
           preference.

           For example, this setting may tell  the  hardware  how  aggressively  or  conservatively  to  control
           frequency  in  the  "turbo range" above the explicitly OS-controlled P-state frequency range.  It may
           also tell the hardware how aggressively it should enter the OS requested C-states.

           This option can be applied to individual cores only via the --cpu option, cpupower(1).

           Setting the performance bias value on one CPU can modify the setting on related  CPUs  as  well  (for
           example  all  CPUs  on one socket), because of hardware restrictions.  Use cpupower -c all info -b to
           verify.

           This options needs the msr kernel driver (CONFIG_X86_MSR) loaded.

SEE ALSO

       cpupower-info(1), cpupower-monitor(1), powertop(1)

AUTHORS

       --perf-bias parts written by Len Brown <len.brown@intel.com>
       Thomas Renninger <trenn@suse.de>

                                                   22/02/2011                                    CPUPOWER-SET(1)