cpupower-set.1 (2280B)
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 ] 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.SH "SEE ALSO" 60cpupower-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> 65Thomas Renninger <trenn@suse.de>