#!/usr/bin/env bash
# KNELPerf day/night resource profile engine.
#
# Broken out of ultix staged/ukrrs-daynight.sh (2026-09-06, #826) and
# redesigned: slice names, devices, and all numeric knobs are CONF-driven
# (no host-specific hardcoding); slice targets are a list so any host can
# run it. Runtime-only changes (set-property --runtime + sysctl + readahead):
# a reboot always lands safely in day mode, because slice unit files carry
# the day defaults (unchanged ultix invariant).
#
# Usage: knelperf-daynight.sh [--conf FILE] day|night
set -euo pipefail

CONF=${KNELPERF_DAYNIGHT_CONF:-/etc/knelperf/daynight.conf}
while [ $# -gt 0 ]; do
  case "$1" in
    --conf) CONF=$2; shift 2 ;;
    day|night) MODE=$1; shift ;;
    *) echo "usage: $0 [--conf FILE] day|night" >&2; exit 2 ;;
  esac
done
[ "${MODE:-}" ] || { echo "usage: $0 [--conf FILE] day|night" >&2; exit 2; }
[ -r "$CONF" ] && . "$CONF"

# Targets: "slice:CPUWeight:AllowedCPUs:MemoryHigh" per mode, space-separated.
# Empty fields mean "skip that property". See knelperf-daynight.conf.example.
: "${DAY_SLICES:=}";  : "${NIGHT_SLICES:=}"
# Block devices for readahead tuning (space-separated; partitions auto-appended).
: "${BLOCK_DEVS:=}"
: "${DATA_RA_DAY:=256}";          : "${DATA_RA_NIGHT:=2048}"
: "${DIRTY_DAY:=1073741824}";     : "${DIRTY_NIGHT:=2147483648}"
: "${DIRTY_BG_DAY:=268435456}";   : "${DIRTY_BG_NIGHT:=536870912}"

log() { echo "[knelperf-daynight] $*"; }
ra=$DATA_RA_DAY; dirty=$DIRTY_DAY; dirtybg=$DIRTY_BG_DAY; slices=$DAY_SLICES
[ "$MODE" = night ] && { ra=$DATA_RA_NIGHT; dirty=$DIRTY_NIGHT; dirtybg=$DIRTY_BG_NIGHT; slices=$NIGHT_SLICES; }

apply_slice() { # "slice:weight:cpus:memhigh"
  local spec=$1 slice weight cpus memhigh
  IFS=: read -r slice weight cpus memhigh <<< "$spec"
  [ -n "$slice" ] || return 0
  local -a props=()
  [ -n "$weight" ]  && props+=(CPUWeight="$weight")
  [ -n "$cpus" ]    && props+=(AllowedCPUs="$cpus")
  [ -n "$memhigh" ] && props+=(MemoryHigh="$memhigh")
  if [ ${#props[@]} -gt 0 ]; then
    systemctl set-property --runtime "$slice" "${props[@]}" \
      || log "WARN: set-property failed for $slice (slice not loaded?)"
  fi
}

for spec in $slices; do apply_slice "$spec"; done

if [ -n "$BLOCK_DEVS" ]; then
  for dev in $BLOCK_DEVS; do
    blockdev --setra "$ra" "$dev" 2>/dev/null || log "readahead skip: $dev"
    for part in "${dev}"[0-9]*; do
      if [ -e "$part" ]; then blockdev --setra "$ra" "$part" 2>/dev/null || true; fi
    done
  done
fi
sysctl -q -w vm.dirty_bytes="$dirty" vm.dirty_background_bytes="$dirtybg"
log "profile $MODE applied $(date -Is)"