1 .TH CPUPOWER\-SET "1" "22/02/2011" "" "cpupower Manual" 2 .SH NAME 3 cpupower\-set \- Set processor power related kernel or hardware configurations 4 .SH SYNOPSIS 5 .ft B 6 .B cpupower set [ \-b VAL ] 7 8 9 .SH DESCRIPTION 10 \fBcpupower set \fP sets kernel configurations or directly accesses hardware 11 registers affecting processor power saving policies. 12 13 Some options are platform wide, some affect single cores. By default values 14 are applied on all cores. How to modify single core configurations is 15 described in the cpupower(1) manpage in the \-\-cpu option section. Whether an 16 option affects the whole system or can be applied to individual cores is 17 described in the Options sections. 18 19 Use \fBcpupower info \fP to read out current settings and whether they are 20 supported on the system at all. 21 22 .SH Options 23 .PP 24 \-\-perf-bias, \-b 25 .RS 4 26 Sets a register on supported Intel processore which allows software to convey 27 its policy for the relative importance of performance versus energy savings to 28 the processor. 29 30 The range of valid numbers is 0-15, where 0 is maximum 31 performance and 15 is maximum energy efficiency. 32 33 The processor uses this information in model-specific ways 34 when it must select trade-offs between performance and 35 energy efficiency. 36 37 This policy hint does not supersede Processor Performance states 38 (P-states) or CPU Idle power states (C-states), but allows 39 software to have influence where it would otherwise be unable 40 to express a preference. 41 42 For example, this setting may tell the hardware how 43 aggressively or conservatively to control frequency 44 in the "turbo range" above the explicitly OS-controlled 45 P-state frequency range. It may also tell the hardware 46 how aggressively it should enter the OS requested C-states. 47 48 This option can be applied to individual cores only via the \-\-cpu option, 49 cpupower(1). 50 51 Setting the performance bias value on one CPU can modify the setting on 52 related CPUs as well (for example all CPUs on one socket), because of 53 hardware restrictions. 54 Use \fBcpupower -c all info -b\fP to verify. 55 56 This options needs the msr kernel driver (CONFIG_X86_MSR) loaded. 57 .RE 58 59 .SH "SEE ALSO" 60 cpupower-info(1), cpupower-monitor(1), powertop(1) 61 .PP 62 .SH AUTHORS 63 .nf 64 \-\-perf\-bias parts written by Len Brown <len.brown@intel.com> 65 Thomas Renninger <trenn@suse.de>
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