GUI or simple Bash script to throttle the CPU?

I have an issue with a Chuwi Hi10 Pro. It occurs in Linux and Windows. When the screen brightness is too high, or the CPU is at 100%, while plugged in, the battery starts to drain. It is a very slow drain using a USB 3.0 QC charger but, I want to keep the tablet on 24/7 fairly reliably.

I would like to know if there is an easy method, preferably GUI or simple Bash script, to throttle the CPU (power management) and go back to high performance mode.

I want to use it for services such as Kodi; it may not mess up the video playback if it is throttled a little.

Side question, other than battery info, is there a way to know the amperage and watts from an AC adapter?

cpuf - Simple Bash GUI to set CPU Min/Max Frequency

Demonstration

In this demo cpuf window is on left and conky system information is on right side. This is how the demo progresses:

Demo starts whilst youtube video is already running
Default CPU min/max frequencies are 800 / 3500
Override CPU min/max to 800 / 800 and CPU usage jumps to 20%
Override CPU min/max to 3500 / 3500 and CPU usage drops to 10%
Demo loops back and starts again

With three monitors cpuf can appear 10 feet away, so use parameter 1 --geometry option to put it close to conky:

sudo cpuf --geometry="450x450+4720+80" /home/rick/Pictures/icons/cpu-intel-128.svg

Parameter 1 --geometry is Window Width x Height + Width Offset + Height Offset
Parameter 2 can be your own icon (in this case Intel CPU image) otherwise it defaults to computer icon

`cpuf` Bash script

This section requires you to open a terminal with Ctrl+Alt+T.

How to setup

In order to function, cpuf bash script requires:

sudo apt install yad         # from the repository universe
sudo apt install coreutils   # installed by default in most distros

It's easiest when you place cpuf script into a root-owned directory within your search path. For example: /usr/local/bin.

To create cpuf script open the editor with sudo -H gedit /usr/local/bin/cpuf.

Highlight the lines in section below
Right click and select "Copy"
Toggle back to your editor
Right click and select "Paste"
From the editor menu select "Save" and then "Exit"

Make the script executable with sudo chmod a+x /usr/local/bin/cpuf.

`cpuf` code to copy to your editor

#!/bin/bash

# NAME: cpuf (Pronounced SEA-PUFF)
# CALL: sudo cpuf
# PARM: $1 = --geometry=WidthxHeight+VertOffset+HorizOffset
#       $2 = Optional image icon

# DESC: Simple GUI script to set CPU Min and Max Frequency.
#       For Ask Ubuntu Question: https://askubuntu.com/q/1141605/307523
# DATE: May 12, 2019.
# UPDT: No updates yet.
# NOTE: No notes yet.

### Dependancies ###

command -v yad >/dev/null 2>&1 || { echo >&2 \
        "yad package required but it is not installed.  Aborting."; \
        exit 1; }

command -v nproc >/dev/null 2>&1 || { echo >&2 \
        "coreutils package required but it is not installed.  Aborting."; \
        exit 2; }

if [[ $(id -u) != 0 ]]; then # root powers needed to call this script
    echo >&2 Must be called with sudo powers
    exit 3
fi

# $TERM variable may be missing when called via desktop shortcut
CurrentTERM=$(env | grep TERM)
if [[ $CurrentTERM == "" ]] ; then
    notify-send --urgency=critical \
    "$0 cannot be run from GUI without TERM environment variable."
    exit 4
fi

### Program constants ###

## Yad Window parameters
# Hard code Height & Width to suit your screen resolution and scaling factor
GEOMETRY="--width 400 --height 500"
# Pass Parameter 1 with ---geometry="WidxHgt+WidOff+HgtOff" to override
[[ "$1" == --geometry=* ]] && GEOMETRY="$1"

TITLE="cpuf"
TEXT="Set CPU Min/Max Frequencies"
ICON="/usr/share/icons/Adwaita/48x48/devices/computer.png"
# Pass Parameter 2 with icon for window image
# Intel CPU comes from: https://www.gnome-look.org/p/1107932/
[[ ! -z "$2" ]] && ICON="$2"

## Virtual File System directories
      CPU0_DIR=/sys/devices/system/cpu/cpu0/cpufreq
    PSTATE_DIR=/sys/devices/system/cpu/intel_pstate
 CURR_MIN_FREQ="$CPU0_DIR/scaling_min_freq"
 CURR_MAX_FREQ="$CPU0_DIR/scaling_max_freq"
ALLOW_MIN_FREQ="$CPU0_DIR/cpuinfo_min_freq"
ALLOW_MAX_FREQ="$CPU0_DIR/cpuinfo_max_freq"

OLD_IFS=$IFS            # Save current Input File Separtor (IFS)
declare -a Arr          # Array for YAD Window input
NumCPU=$(nproc --all)   # Number of CPUs (nproc from coreutils)

### Error Message Functions ###

Abend () {
    # Abnormal Ending - Parameter 1 = message to display, Parameter 2=exit code

    yad --image "dialog-error" --image-on-top --title "$TITLE - Fatal Error" \
        "$GEOMETRY" --button=gtk-ok:0 --text "$1" 2>/dev/null
    exit "$2"
   
} # Abend

ErrMsg () {
    # Parmater 1 = message to display

    yad --image "dialog-error" --title "$TITLE - Logical Error" \
        "$GEOMETRY" --button=gtk-ok:0 --text "$1" 2>/dev/null

    fErrMsgForceContinue=true
 
} # ErrMsg

### Initialize Variables ###

InitVars () {

    [[ ! -e "$ALLOW_MIN_FREQ" ]] && Abend "$ALLOW_MIN_FREQ not found" 11
    AllowMinFreq=$(cat "$ALLOW_MIN_FREQ")
    AllowMinFreq="${AllowMinFreq::-3}"  # Chop off three decimals at end

    [[ ! -e "$ALLOW_MAX_FREQ" ]] && Abend "$ALLOW_MAX_FREQ not found" 12
    AllowMaxFreq=$(cat "$ALLOW_MAX_FREQ")
    AllowMaxFreq="${AllowMaxFreq::-3}"

    [[ ! -e "$CURR_MIN_FREQ" ]] && Abend "$CURR_MIN_FREQ not found" 13
    CurrMinFreq=$(cat "$CURR_MIN_FREQ")
    CurrMinFreq="${CurrMinFreq::-3}"
    NewMinFreq="$CurrMinFreq"

    [[ ! -e "$CURR_MAX_FREQ" ]] && Abend "$CURR_MAX_FREQ not found" 14
    CurrMaxFreq=$(cat "$CURR_MAX_FREQ")
    CurrMaxFreq="${CurrMaxFreq::-3}"
    NewMaxFreq="$CurrMaxFreq"

    if [[ -e "$PSTATE_DIR" ]] ; then
        NumPstates=$(cat "$PSTATE_DIR/num_pstates")
        if [[ $(cat "$PSTATE_DIR/no_turbo") -eq 0 ]] ; then
            TurboBoost="Enabled"
        else
            TurboBoost="Disabled"
        fi
    else
        NumPstates="Not found"
        TurboBoost="Not found"
    fi

    if [[ -e "$CPU0_DIR/scaling_governor" ]] ; then
        Governor=$(cat "$CPU0_DIR/scaling_governor")
    else
        Governor="Not found"
    fi

    if [[ -e "$CPU0_DIR/scaling_cur_freq" ]] ; then
        CurrFreq=$(cat "$CPU0_DIR/scaling_cur_freq")
        # Chop off three decimals at end
        CurrFreq="${CurrFreq::-3}"
    else
        CurrFreq="Not found"
    fi

} # InitVars

### Paint / repaint window and get new frequencies ###

GetParameters () {

    # +------------------------------------------+
    # |  cpuf - Set CPU Min/Max Frequencies      |
    # +------------------------------------------+
    # |                                          |
    # |  Turbo Boost:            Enabled         |
    # |                                          |
    # |  Number of pstates:      99              |
    # |  Speed Governor Used:    powersave       |
    # |  Current CPU0 frequency: 9999 Mhz        |
    # |                                          |
    # |  Current Minimum Freq.:  9999 Mhz        |
    # |  Current Maximum Freq.:  9999 Mhz        |
    # |                                          |
    # |  New Minimum Frequency   9999            |
    # |  New Maximum Frequency   9999            |
    # |                                          |
    # +------------------------------------------+

    IFS="|"
    Arr=($(yad "$GEOMETRY" --form \
        --title "$TITLE" --text "$TEXT" \
        --window-icon="$ICON" --image="$ICON" \
        --field="Turbo Boost:":RO "$TurboBoost" \
        --field="Number of pstates:":RO "$NumPstates" \
        --field="Speed Governor:":RO "$Governor" \
        --field="Current Frequency:":RO "$CurrFreq MHz" \
        --field="Allowable Minimum Frequency:":RO "$AllowMinFreq MHz" \
        --field="Allowable Maximum Frequency:":RO "$AllowMaxFreq MHz" \
        --field="Current Minimum Frequency:":RO "$CurrMinFreq MHz" \
        --field="Current Maximum Frequency:":RO "$CurrMaxFreq MHz" \
        --field="New Minimum Frequency" "$NewMinFreq" \
        --field="New Maximum Frequency" "$NewMaxFreq" 2>/dev/null))

    Return="$?"
    NewMinFreq="${Arr[8]}"
    NewMaxFreq="${Arr[9]}"

} # GetParameters

###################################
#            MAINLINE             #
###################################

ALL_PREFIX="/sys/devices/system/cpu/cpu"
MIN_SUFFIX="/cpufreq/scaling_min_freq"
MAX_SUFFIX="/cpufreq/scaling_max_freq"

while true ; do

    InitVars
    GetParameters
    [[ ! "$Return" -eq 0 ]] && break ; # Exit on Cancel=1 or Close Window=252

    # Sanity checks
    fErrMsgForceContinue=false
    [[ $NewMinFreq -lt $AllowMinFreq ]] && ErrMsg "Minimum frequency too low"
    [[ $NewMaxFreq -gt $AllowMaxFreq ]] && ErrMsg "Maximum frequency too high"
    [[ $NewMinFreq -gt $NewMaxFreq ]]   && ErrMsg "Minimum frequency greater than Maximum Frequency"
    [[ $fErrMsgForceContinue == true ]] && continue
    
    # Set new Min/Max frequencies
    for (( i=0 ; i<NumCPU ; i++ )) ; do
        # If New Min > Curr Max, set Max first then Min
        if [[ $NewMinFreq -gt $CurrMaxFreq ]] ; then
            echo "$NewMaxFreq""000" > "$ALL_PREFIX$i$MAX_SUFFIX"
            echo "$NewMinFreq""000" > "$ALL_PREFIX$i$MIN_SUFFIX"
        else
            echo "$NewMinFreq""000" > "$ALL_PREFIX$i$MIN_SUFFIX"
            echo "$NewMaxFreq""000" > "$ALL_PREFIX$i$MAX_SUFFIX"
        fi
    done
    

done

IFS="$OLD_IFS"
exit 0

GUI or simple Bash script to throttle the CPU?

cpuf - Simple Bash GUI to set CPU Min/Max Frequency

Demonstration

`cpuf` Bash script

How to setup

`cpuf` code to copy to your editor

Related

Recent Posts

GUI or simple Bash script to throttle the CPU?

cpuf - Simple Bash GUI to set CPU Min/Max Frequency

Demonstration

cpuf Bash script

How to setup

cpuf code to copy to your editor

Related

Recent Posts

`cpuf` Bash script

`cpuf` code to copy to your editor