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1.TH CPUPOWER\-SET "1" "22/02/2011" "" "cpupower Manual"2.SH NAME3cpupower\-set \- Set processor power related kernel or hardware configurations4.SH SYNOPSIS5.ft B6.B cpupower set [ \-b VAL ]7 8 9.SH DESCRIPTION10\fBcpupower set \fP sets kernel configurations or directly accesses hardware11registers affecting processor power saving policies.12 13Some options are platform wide, some affect single cores. By default values14are applied on all cores. How to modify single core configurations is15described in the cpupower(1) manpage in the \-\-cpu option section. Whether an16option affects the whole system or can be applied to individual cores is17described in the Options sections.18 19Use \fBcpupower info \fP to read out current settings and whether they are20supported on the system at all.21 22.SH Options23.PP24\-\-perf-bias, \-b25.RS 426Sets a register on supported Intel processore which allows software to convey27its policy for the relative importance of performance versus energy savings to28the processor.29 30The range of valid numbers is 0-15, where 0 is maximum31performance and 15 is maximum energy efficiency.32 33The processor uses this information in model-specific ways34when it must select trade-offs between performance and35energy efficiency.36 37This policy hint does not supersede Processor Performance states38(P-states) or CPU Idle power states (C-states), but allows39software to have influence where it would otherwise be unable40to express a preference.41 42For example, this setting may tell the hardware how43aggressively or conservatively to control frequency44in the "turbo range" above the explicitly OS-controlled45P-state frequency range. It may also tell the hardware46how 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 on52related CPUs as well (for example all CPUs on one socket), because of53hardware restrictions.54Use \fBcpupower -c all info -b\fP to verify.55 56This options needs the msr kernel driver (CONFIG_X86_MSR) loaded.57.RE58 59.SH "SEE ALSO"60cpupower-info(1), cpupower-monitor(1), powertop(1)61.PP62.SH AUTHORS63.nf64\-\-perf\-bias parts written by Len Brown <len.brown@intel.com>65Thomas Renninger <trenn@suse.de>66