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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 configurations is described in the cpupower(1) man-
       page 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 sys-
       tem at all.

Options
       --perf-bias, -b
	   Sets a register on supported Intel processore which allows software to convey its pol-
	   icy	for  the relative importance of performance versus energy savings to the  proces-
	   sor.

	   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 fre-
	   quency 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,	frequency  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)
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