cpupower-set.1

  1.TH CPUPOWER\-SET "1" "22/02/2011" "" "cpupower Manual"
  2.SH NAME
  3cpupower\-set \- Set processor power related kernel or hardware configurations
  4.SH SYNOPSIS
  5.ft B
  6.B cpupower set [ \-b VAL | \-e POLICY | \-m MODE | \-t BOOL ]
  7
  8
  9.SH DESCRIPTION
 10\fBcpupower set \fP sets kernel configurations or directly accesses hardware
 11registers affecting processor power saving policies.
 12
 13Some options are platform wide, some affect single cores. By default values
 14are applied on all cores. How to modify single core configurations is
 15described in the cpupower(1) manpage in the \-\-cpu option section. Whether an
 16option affects the whole system or can be applied to individual cores is
 17described in the Options sections.
 18
 19Use \fBcpupower info \fP to read out current settings and whether they are
 20supported on the system at all.
 21
 22.SH OPTIONS
 23.PP
 24\-\-perf-bias, \-b
 25.RS 4
 26Sets a register on supported Intel processore which allows software to convey
 27its policy for the relative importance of performance versus energy savings to
 28the  processor.
 29
 30The range of valid numbers is 0-15, where 0 is maximum
 31performance and 15 is maximum energy efficiency.
 32
 33The processor uses this information in model-specific ways
 34when it must select trade-offs between performance and
 35energy efficiency.
 36
 37This policy hint does not supersede Processor Performance states
 38(P-states) or CPU Idle power states (C-states), but allows
 39software to have influence where it would otherwise be unable
 40to express a preference.
 41
 42For example, this setting may tell the hardware how
 43aggressively or conservatively to control frequency
 44in the "turbo range" above the explicitly OS-controlled
 45P-state frequency range.  It may also tell the hardware
 46how aggressively it should enter the OS requested C-states.
 47
 48This option can be applied to individual cores only via the \-\-cpu option,
 49cpupower(1).
 50
 51Setting the performance bias value on one CPU can modify the setting on
 52related CPUs as well (for example all CPUs on one socket), because of
 53hardware restrictions.
 54Use \fBcpupower -c all info -b\fP to verify.
 55
 56This options needs the msr kernel driver (CONFIG_X86_MSR) loaded.
 57.RE
 58
 59.PP
 60\-\-epp, \-e
 61.RS 4
 62Sets the energy performance policy preference on supported Intel or AMD
 63processors which use the Intel or AMD P-State cpufreq driver respectively.
 64
 65Available policies can be found with
 66\fBcat /sys/devices/system/cpu/cpufreq/policy0/energy_performance_available_preferences\fP :
 67.RS 4
 68default performance balance_performance balance_power power
 69.RE
 70
 71.RE
 72
 73.PP
 74\-\-amd\-pstate\-mode, \-m
 75.RS 4
 76Sets the AMD P-State mode for supported AMD processors.
 77Available modes are "active", "guided" or "passive".
 78
 79Refer to the AMD P-State kernel documentation for further information.
 80
 81.RE
 82
 83.PP
 84\-\-turbo\-boost, \-\-boost, \-t
 85.RS 4
 86This option is used to enable or disable the boost feature on
 87supported Intel and AMD processors, and other boost supported systems.
 88(The --boost option is an alias for the --turbo-boost option)
 89
 90This option takes as parameter either \fB1\fP to enable, or \fB0\fP to disable the feature.
 91
 92.RE
 93
 94.SH "SEE ALSO"
 95cpupower-info(1), cpupower-monitor(1), powertop(1)
 96.PP
 97.SH AUTHORS
 98.nf
 99\-\-perf\-bias parts written by Len Brown <len.brown@intel.com>
100Thomas Renninger <trenn@suse.de>