#!/usr/bin/env zsh
#
# Pressure Stall Information monitor
#
#    Copyright © 2023 Trey Blancher $(base64 -d <<< dHJleUBibGFuY2hlci5uZXQK)
#
#    This program is free software: you can redistribute it and/or modify it
#    under the terms of the GNU General Public License as published by the Free
#    Software Foundation, either version 3 of the License, or (at your option)
#    any later version.
#
#    This program is distributed in the hope that it will be useful, but
#    WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
#    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
#    for more details.
#
#    You should have received a copy of the GNU General Public License along
#    with this program.  If not, see <https://www.gnu.org/licenses/>.
#
#    Submodules may be distributed under a separate software license;  see the
#    LICENSE file within each submodule.
# 
# This script monitors the three pressure stall information files
# /proc/pressure{cpu,io,memory} and reports if any resource is above threshold
# for the "some" values.  It takes an optional single argument, the threshold at
# which to alert.  If this is not supplied, it defaults to a threshold of 30.0 
# percent.
#

local cpu="/proc/pressure/cpu"
local cpu_ctr=0
local io="/proc/pressure/io"
local io_ctr=0
local mem="/proc/pressure/memory"
local mem_ctr=0
local threshold=30.0

if [[ -n "${1}" ]]; then
    threshold=${1}
fi

# main loop
while true; do
    local cpu_pct=$(grep 'some' ${cpu} | awk '{print $2}' | awk -F'=' '{print $2}')    
    local io_pct=$(grep 'some' ${io} | awk '{print $2}' | awk -F'=' '{print $2}')    
    local mem_pct=$(grep 'some' ${mem} | awk '{print $2}' | awk -F'=' '{print $2}')    
    
    if (( cpu_pct > threshold )); then
        cpu_ctr=$(( ${cpu_ctr} + 1 ))
        printf "CPU PSI event %d triggered.\n" ${cpu_ctr}
    fi
    if (( io_pct > threshold )); then
        io_ctr=$(( ${io_ctr} + 1 ))
        printf "IO PSI event %d triggered.\n" ${io_ctr}
    fi
    if (( mem_pct > threshold )); then
        mem_ctr=$(( ${mem_ctr} + 1 ))
        printf "MEM PSI event %d triggered.\n" ${mem_ctr}
    fi

    sleep 10
done