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authorDominik Brodowski <linux@dominikbrodowski.net>2011-03-30 16:30:11 +0200
committerDominik Brodowski <linux@dominikbrodowski.net>2011-07-29 18:35:36 +0200
commit7fe2f6399a84760a9af8896ac152728250f82adb (patch)
treefa4bf236359b8d6d9f8d6ff823ddd3e839da5768 /tools/power/cpupower/man/cpupower-set.1
parentLinux 3.0 (diff)
downloadlinux-7fe2f6399a84760a9af8896ac152728250f82adb.tar.xz
linux-7fe2f6399a84760a9af8896ac152728250f82adb.zip
cpupowerutils - cpufrequtils extended with quite some features
CPU power consumption vs performance tuning is no longer limited to CPU frequency switching anymore: deep sleep states, traditional dynamic frequency scaling and hidden turbo/boost frequencies are tied close together and depend on each other. The first two exist on different architectures like PPC, Itanium and ARM, the latter (so far) only on X86. On X86 the APU (CPU+GPU) will only run most efficiently if CPU and GPU has proper power management in place. Users and Developers want to have *one* tool to get an overview what their system supports and to monitor and debug CPU power management in detail. The tool should compile and work on as many architectures as possible. Once this tool stabilizes a bit, it is intended to replace the Intel-specific tools in tools/power/x86 Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
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+.TH CPUPOWER\-SET "1" "22/02/2011" "" "cpupower Manual"
+.SH NAME
+cpupower\-set \- Set processor power related kernel or hardware configurations
+.SH SYNOPSIS
+.ft B
+.B cpupower set [ \-b VAL ] [ \-s VAL ] [ \-m VAL ]
+
+
+.SH DESCRIPTION
+\fBcpupower set \fP 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) 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 \fBcpupower info \fP to read out current settings and whether they are
+supported on the system at all.
+
+.SH Options
+.PP
+\-\-perf-bias, \-b
+.RS 4
+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 \fBcpupower -c all info -b\fP to verify.
+
+This options needs the msr kernel driver (CONFIG_X86_MSR) loaded.
+.RE
+.PP
+\-\-sched\-mc, \-m [ VAL ]
+.RE
+\-\-sched\-smt, \-s [ VAL ]
+.RS 4
+\-\-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:
+.RS 2
+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
+.RE
+
+sched_mc_power_savings is dependent upon SCHED_MC, which is
+itself architecture dependent.
+
+sched_smt_power_savings is dependent upon SCHED_SMT, which
+is itself architecture dependent.
+
+The two files are independent of each other. It is possible
+that one file may be present without the other.
+
+.SH "SEE ALSO"
+cpupower-info(1), cpupower-monitor(1), powertop(1)
+.PP
+.SH AUTHORS
+.nf
+\-\-perf\-bias parts written by Len Brown <len.brown@intel.com>
+Thomas Renninger <trenn@suse.de>