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

NAME

       cpupower-set - Set processor power related kernel or hardware configurations

SYNOPSIS

       cpupower set [ -b VAL ] [ -s VAL ] [ -m 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 section. 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 setting 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.

       --sched-mc,  -m [ VAL ]
       --sched-smt, -s [ VAL ]
	   --sched-mc utilizes cores in one processor package/socket first before processes are scheduled to other processor packages/sockets.

	   --sched-smt utilizes thread siblings of one processor core first before processes are scheduled to other cores.

	   The impact on power consumption and performance (positiv or negativ) heavily depends on processor support for deep sleep  states,  fre-
	   quency scaling and frequency boost modes and their dependencies between other thread siblings and processor cores.

	   Taken over from kernel documentation:

	   Adjust the kernel's multi-core scheduler support.

	   Possible values are:
	     0 - No power saving load balance (default value)

	     1 - Fill one thread/core/package first for long running threads

	     2 - Also bias task wakeups to semi-idle cpu package for power savings

SEE ALSO

       cpupower-info(1), cpupower-monitor(1), powertop(1)

AUTHORS

       --perf-bias parts written by Len Brown <len.brown@intel.com>
       Thomas Renninger <trenn@suse.de>

								    22/02/2011							   CPUPOWER-SET(1)