Script to set MLX memory limits

set_wired_limits.sh

#!/usr/bin/env bash
set -euo pipefail

DEFAULT_WIRED_LIMIT_PERCENT=85
DEFAULT_WIRED_LWM_PERCENT=75

usage() {
  cat <<'EOF'
Usage: set_wired_limits.sh [MAX_PERCENT] [LWM_PERCENT] [--apply]
- MAX_PERCENT: upper bound percent (0-100), default 85
- LWM_PERCENT: lower bound percent (0-100), default 75
- --apply: actually write values via sysctl (otherwise dry-run)
EOF
}

APPLY=0
ARGS=()
for arg in "$@"; do
  case "$arg" in
    --apply) APPLY=1 ;;
    -h|--help) usage; exit 0 ;;
    *) ARGS+=("$arg") ;;
  esac
done

WIRED_LIMIT_PERCENT=${ARGS[0]:-$DEFAULT_WIRED_LIMIT_PERCENT}
WIRED_LWM_PERCENT=${ARGS[1]:-$DEFAULT_WIRED_LWM_PERCENT}

if ! [[ "$WIRED_LIMIT_PERCENT" =~ ^[0-9]+$ && "$WIRED_LWM_PERCENT" =~ ^[0-9]+$ ]]; then
  echo "Error: Percentages must be integers." >&2
  exit 1
fi

if (( WIRED_LIMIT_PERCENT < 0 || WIRED_LIMIT_PERCENT > 100 || WIRED_LWM_PERCENT < 0 || WIRED_LWM_PERCENT > 100 )); then
  echo "Error: Percentages must be between 0 and 100." >&2
  exit 1
fi

TOTAL_MEM_MB=$(( $(sysctl -n hw.memsize) / 1024 / 1024 ))
WIRED_LIMIT_MB=$(( TOTAL_MEM_MB * WIRED_LIMIT_PERCENT / 100 ))
WIRED_LWM_MB=$(( TOTAL_MEM_MB * WIRED_LWM_PERCENT / 100 ))

echo "Total memory: ${TOTAL_MEM_MB} MB"
echo "Maximum limit: ${WIRED_LIMIT_MB} MB (${WIRED_LIMIT_PERCENT}%) -> sysctl key: iogpu.wired_limit_mb"
echo "Lower bound:  ${WIRED_LWM_MB} MB (${WIRED_LWM_PERCENT}%) -> sysctl key: iogpu.wired_lwm_mb"

if (( APPLY )); then
  echo "Applying settings (sudo required)…"
  sudo sysctl -w iogpu.wired_limit_mb="$WIRED_LIMIT_MB"
  sudo sysctl -w iogpu.wired_lwm_mb="$WIRED_LWM_MB"
  echo "Done."
else
  echo "Dry-run only. Re-run with --apply to write values."
fi

Adds  set -euo pipefail  for safer shell execution.

• Validates integer input and range before doing any work.
• Dry-run by default reduces accidental writes;  --apply  is explicit.
• Help/usage text for quick reference.

Testing guidance:

• Dry-run with defaults:  ./set_wired_limits.sh 
• Dry-run custom:  ./set_wired_limits.sh 80 70 
• Apply after review:  ./set_wired_limits.sh 80 70 --apply 
• Error cases:  ./set_wired_limits.sh 110  should exit with validation error.