.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 ] .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 .SH "SEE ALSO" cpupower-info(1), cpupower-monitor(1), powertop(1) .PP .SH AUTHORS .nf \-\-perf\-bias parts written by Len Brown Thomas Renninger value='grep'>log msg
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authorSteven Rostedt (VMware) <rostedt@goodmis.org>2017-01-30 19:27:10 -0500
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2017-01-31 09:13:49 -0500
commit79c6f448c8b79c321e4a1f31f98194e4f6b6cae7 (patch)
tree370efda701f03cccf21e02bb1fdd3b852547d75c /tools/firewire
parent0c744ea4f77d72b3dcebb7a8f2684633ec79be88 (diff)
tracing: Fix hwlat kthread migration
The hwlat tracer creates a kernel thread at start of the tracer. It is pinned to a single CPU and will move to the next CPU after each period of running. If the user modifies the migration thread's affinity, it will not change after that happens. The original code created the thread at the first instance it was called, but later was changed to destroy the thread after the tracer was finished, and would not be created until the next instance of the tracer was established. The code that initialized the affinity was only called on the initial instantiation of the tracer. After that, it was not initialized, and the previous affinity did not match the current newly created one, making it appear that the user modified the thread's affinity when it did not, and the thread failed to migrate again. Cc: stable@vger.kernel.org Fixes: 0330f7aa8ee6 ("tracing: Have hwlat trace migrate across tracing_cpumask CPUs") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'tools/firewire')