huschi.net

CPUPOWER-SET(1)                 cpupower Manual                CPUPOWER-SET(1)

NAME
       cpupower-set  - Set processor power related kernel or hardware configu-
       rations
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  configura-
       tions  is described in the cpupower(1) manpage in the --cpu option sec-
       tion. 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  set-
           ting  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 AT intel.com>
       Thomas Renninger <trenn AT suse.de>

                                  22/02/2011                   CPUPOWER-SET(1)