power.py is a Python script that allows you to configure
specific cores using command line parameters or an easy-to-use menu.
It allows adjustment of P-States and C-States through the
Linux kernel /proc file system interface.
This script works with both acpi-cpufreq and intel_pstate drivers, although
functionality may be slightly different between them. If you wish to
disable the intel_pstate kernel driver, we need to
add intel_pstate=disable to the kernel boot parameters. Typically this is
done by editing /boot/grub2/grub.cfg or /etc/default/grub, and adding
to the relevant kernel parameter line (it may be slightly different on
different operating systems).
GRUB_CMDLINE_LINUX_DEFAULT="net.ifnames=0 intel_pstate=disable ..."After making updates, a new grub file needs to be generated and a reboot is required. For example, on Ubuntu:
update-grub
rebootCertain cores may need more performance than others, so in this case those cores could have Turbo Boost enabled, while leaving the rest of the cores at P1 (or lower). P1 is the maximum non-turbo frequency.
For applications utilizing DPDK, the mechanisms for passing packets around a system usually involves busy polling, which the intel_pstate driver sees as 100% busy and will be unable to scale down the frequency of any of the cores to save power. In this case it is possible to use the userspace governor, and force the frequencey of the cores down during quiet periods to save power.
The script is compatible with Intel® Xeon® CPU E5 v3, Intel® Xeon® CPU E5 v4, and Intel® Xeon® Processor Scalable Family among others.
There are two modes of operation of the script. One method is via command line paramters, allowing the script to be called from other scripts, binaries, etc. The other method is via interactive menu, which is invoked when no command line parameters are given.
When executing the script with the '-h' command line parameter, the user is presented with help text:
# power.py -h
/usr/local/sbin/power.py -i -M <maxfreq> -m <minfreq> -s <setfreq> -r <range> -g <governor>
<no params> use interactive menu
-h Show this help
-i Show information on available freqs, C-States, etc
-l List information on each core
-L <sec> List information on each core repeatedly at <sec> intervals
-M <freq> Set core maximum frequency. Can also use "max", "min", or "base"
-m <freq> Set core minimum frequency. Can also use "max", "min", or "base"
-s <freq> Set core frequency (within min and max)
-r <range> Range of cores to affect, e.g. 1-3,5,7
-g <governor> Set core governor (usually 'userspace')
-e <cstate> Enable core C-State
-d <cstate> Disable core C-State
-U <freq> Set uncore maximum frequency
-u <freq> Set uncore minimum frequency
-T Enable Turbo
-t Disable Turbo
Examples:
1. Set governor to ondemand, min 1GHz, max 2.5GHz, cores 0-10
/usr/local/bin/power.py -g ondemand -r 0-10 -M 2500 -m 1000
2. Set governor to userspace, cores 2 and 4 only, set freq to 2GHz
/usr/local/bin/power.py -g userspace -r 2,4 -s 2000
3. Set governor to userspace, core 1, set freq to Turbo Boost
this assumes there's a 2501 and a 2500 freq available.
/usr/local/bin/power.py -g userspace -r 1 -M 2501 -s 2501When executing the script without any command line parameters, the user is presented with the following menu:
# power.py
----------------------------------------------------------
[1] Display Available Settings
[2] Display Current Settings
[3] Display Available P-States
[4] Set P-State governor for a range of cores
[5] Set Maximum P-State for a range of cores
[6] Set Minimum P-State for a range of cores
[7] Display Available C-States
[8] Enable C-State for a range of cores
[9] Disable C-State for a range of cores
[10] Display Available Uncore Freqs
[11] Set Uncore Maximum for a range of cores
[12] Set Uncore Minimum for a range of cores
[13] Enable Turbo
[14] Disable Turbo
[h] Show Help Text
[q] Exit Script
----------------------------------------------------------
Option:The first two menu options are informational, one giving the available settings, and the other displaying a table with the current system settings.
[1] Display Available Settings
Option: 1
P-State Driver: intel_pstate
CPU Base Frequency: 1900MHz
Available P-States: [3600, 3500, 3400, 3300, 3200, 3100, 3000, 2900, 2800, 2700, 2600, 2500, 2400, 2300, 2200, 2100, 2000, 1900, 1800, 1700, 1600, 1500, 1400, 1300, 1200, 1100, 1000, 900, 800]
Turbo Available: Yes (any pstate above '1900'): Enabled
Number of CPUs: 64
Available Governors: ['performance', 'powersave']
Available C-States: ['C6', 'C1', 'C1E', 'POLL']
Press enter to continue ...Note: The output produced varies based on system configuration, not all governors will always be available.
[2] Display Current Settings
Option: 2
==== ================================ =============================== ========================
P-STATE INFO C-STATES DISABLED? UNCORE INFO
Core Max Min Now Governor POLL C1 C1E C6 Max Min Now
==== ====== ====== ====== =========== ======= ======= ======= ======= ======= ======== =======
0 3600 800 800 powersave no no no no 2500 800 800
1 3600 800 1900 powersave no no no no 2500 800 800
2 3600 800 799 powersave no no no no 2500 800 800
3 3600 800 1900 powersave no no no no 2500 800 800
4 3600 800 1900 powersave no no no no 2500 800 800
5 3600 800 1900 powersave no no no no 2500 800 800
6 3600 800 1900 powersave no no no no 2500 800 800
7 3600 800 800 powersave no no no no 2500 800 800
8 3600 800 1900 powersave no no no no 2500 800 800
9 3600 800 1900 powersave no no no no 2500 800 800
10 3600 800 800 powersave no no no no 2500 800 800
11 3600 800 1900 powersave no no no no 2500 800 800
12 3600 800 1900 powersave no no no no 2500 800 800
13 3600 800 1900 powersave no no no no 2500 800 800
14 3600 800 1900 powersave no no no no 2500 800 800
15 3600 800 1900 powersave no no no no 2500 800 800
16 3600 800 800 powersave no no no no 2500 800 800
17 3600 800 1900 powersave no no no no 2500 800 800
18 3600 800 1900 powersave no no no no 2500 800 800
19 3600 800 1900 powersave no no no no 2500 800 800
20 3600 800 1900 powersave no no no no 2500 800 800
21 3600 800 1900 powersave no no no no 2500 800 800
22 3600 800 1900 powersave no no no no 2500 800 800The remaining options allow settings of P-States (core frequency) and C-States (core sleep states)
The P-State settings allow per-core settings of the P-State governor, maximum frequency, minimum frequency, and the set frequency. Typically this involves the user selecting an option from a list of available values, followed by the user entering a range of cores to which to apply the setting.
Option: 4
[1] performance
[2] powersave
Select Governor: 1
Input Range of Cores: 5-10,14,20
Working with cores: [5, 6, 7, 8, 9, 10, 14, 20]
Writing 'performance' to /sys/devices/system/cpu/cpu5/cpufreq/scaling_governor
Writing 'performance' to /sys/devices/system/cpu/cpu6/cpufreq/scaling_governor
Writing 'performance' to /sys/devices/system/cpu/cpu7/cpufreq/scaling_governor
Writing 'performance' to /sys/devices/system/cpu/cpu8/cpufreq/scaling_governor
Writing 'performance' to /sys/devices/system/cpu/cpu9/cpufreq/scaling_governor
Writing 'performance' to /sys/devices/system/cpu/cpu10/cpufreq/scaling_governor
Writing 'performance' to /sys/devices/system/cpu/cpu14/cpufreq/scaling_governor
Writing 'performance' to /sys/devices/system/cpu/cpu20/cpufreq/scaling_governor
Press enter to continue ...Note that the range of cores can include ranges and specific cores, seperated by commas. For example the input "5-10,14,20" is expanded out to cores "5, 6, 7, 8, 9, 10, 14, 20", and then the setting is applied to each of those cores.
The C-State settings allow the enable/disable of any C-State except C0, which is the POLL C-state. Any other C-State is a sleep state, and may be enabled/disabled.
Option: 8
[1] C6
[2] C1
[3] C1E
[4] POLL
Select C-State: 3
Input Range of Cores: 0-4
Working with cores: [0, 1, 2, 3, 4]
Writing '0' to /sys/devices/system/cpu/cpu0/cpuidle/state2/disable
Writing '0' to /sys/devices/system/cpu/cpu1/cpuidle/state2/disable
Writing '0' to /sys/devices/system/cpu/cpu2/cpuidle/state2/disable
Writing '0' to /sys/devices/system/cpu/cpu3/cpuidle/state2/disable
Writing '0' to /sys/devices/system/cpu/cpu4/cpuidle/state2/disable
Press enter to continue ...Note that when changing C-State settings, there is an option to select all, allowing the convenient enable/disable of all non-POLL C-States in one step.
The Uncore Freqs settings allow setting of the maximum and minimum range of Uncore Frequencies and also displays available Uncore Frequencies.
Option: 11
Available uncore freqs: [2500, 2400, 2300, 2200, 2100, 2000, 1900, 1800, 1700, 1600, 1500, 1400, 1300, 1200, 1100, 1000, 900, 800]
Input UncoreFreq: 2000
Press enter to continue ...Please see the help text provided by the script for examples of using the command line parameters.