1CPUPOWER-SET(1) cpupower Manual CPUPOWER-SET(1)
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6 cpupower-set - Set processor power related kernel or hardware configu‐
7 rations
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10 cpupower set [ -b VAL ] [ -s VAL ]
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15 cpupower set sets kernel configurations or directly accesses hardware
16 registers affecting processor power saving policies.
17 Some options are platform wide, some affect single cores. By default
19 values are applied on all cores. How to modify single core configura‐
20 tions is described in the cpupower(1) manpage in the --cpu option sec‐
21 tion. Whether an option affects the whole system or can be applied to
22 individual cores is described in the Options sections.
23 Use cpupower info to read out current settings and whether they are
25 supported on the system at all.
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29 --perf-bias, -b
30 Sets a register on supported Intel processore which allows software
31 to convey its policy for the relative importance of performance
32 versus energy savings to the processor.
33 The range of valid numbers is 0-15, where 0 is maximum performance
35 and 15 is maximum energy efficiency.
36 The processor uses this information in model-specific ways when it
38 must select trade-offs between performance and energy efficiency.
39 This policy hint does not supersede Processor Performance states
41 (P-states) or CPU Idle power states (C-states), but allows software
42 to have influence where it would otherwise be unable to express a
43 preference.
44 For example, this setting may tell the hardware how aggressively or
46 conservatively to control frequency in the "turbo range" above the
47 explicitly OS-controlled P-state frequency range. It may also tell
48 the hardware how aggressively it should enter the OS requested C-
49 states.
50 This option can be applied to individual cores only via the --cpu
52 option, cpupower(1).
53 Setting the performance bias value on one CPU can modify the set‐
55 ting on related CPUs as well (for example all CPUs on one socket),
56 because of hardware restrictions. Use cpupower -c all info -b to
57 verify.
58 This options needs the msr kernel driver (CONFIG_X86_MSR) loaded.
60 --sched-smt, -s [ VAL ]
62 --sched-smt utilizes thread siblings of one processor core first
64 before processes are scheduled to other cores.
65 The impact on power consumption and performance (positiv or nega‐
67 tiv) heavily depends on processor support for deep sleep states,
68 frequency scaling and frequency boost modes and their dependencies
69 between other thread siblings and processor cores.
70 Taken over from kernel documentation:
72 Adjust the kernel's multi-core scheduler support.
74 Possible values are:
76 0 - No power saving load balance (default value)
77 1 - Fill one thread/core/package first for long running threads
79 2 - Also bias task wakeups to semi-idle cpu package for power
81 savings
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85 cpupower-info(1), cpupower-monitor(1), powertop(1)
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88 --perf-bias parts written by Len Brown <len.brown@intel.com>
89 Thomas Renninger <trenn@suse.de>
90 22/02/2011 CPUPOWER-SET(1)