#!/bin/bash # ============================================================================= # RPi5 Lab 01 - Memory swap setup for Ubuntu Server 24.04 # ============================================================================= # The Pi 5 ships with 2-16 GB of RAM. apt installs of ROS 2 are fine without # swap, but building a workspace from source with colcon (C++ packages # especially) can run out of memory and get killed partway through. # # zram - compressed swap that lives in RAM. Fast, no SD card wear. # file - a swap file (/swapfile) on the SD card. Slower, but real extra # capacity that does not compete with RAM. # # Ubuntu does not use dphys-swapfile like Raspberry Pi OS - the swap file is # created directly and listed in /etc/fstab. zram is started by a systemd # service, so nothing can hang the boot. # # USAGE # sudo bash setup_swap.sh # set up swap # sudo bash setup_swap.sh --status # just show current swap # sudo bash setup_swap.sh --uninstall # undo # # Run this ON THE ROBOT (over SSH is fine). No reboot needed. # ============================================================================= # ----------------------------- SETTINGS -------------------------------------- SWAP_MODE="both" # "both" (recommended) | "zram" | "file" ZRAM_FACTOR=1 # total zram = this x RAM FILE_SWAP_MB=2048 # size of /swapfile on the SD card RECOMMENDED_MB=4000 # RAM + swap worth having before building ROS 2 packages # ----------------------------------------------------------------------------- set -u SWAPFILE=/swapfile ZRAM_SCRIPT=/usr/local/bin/robot-zram.sh ZRAM_UNIT=/etc/systemd/system/robot-zram.service say() { echo -e "\n\033[1;36m==> $*\033[0m"; } ok() { echo -e " \033[1;32mOK\033[0m $*"; } warn() { echo -e " \033[1;33m!!\033[0m $*"; } die() { echo -e "\n\033[1;31mERROR:\033[0m $*\n" >&2; exit 1; } show_status() { echo free -h echo echo "Active swap devices:" cat /proc/swaps TOTAL_MB=$(free -m | awk '/^Mem:/{m=$2} /^Swap:/{s=$2} END{print m+s}') echo echo "Total memory + swap: ${TOTAL_MB} MB" if [ "$TOTAL_MB" -ge "$RECOMMENDED_MB" ]; then echo -e "\033[1;32mThat is enough for building ROS 2 packages on the Pi.\033[0m" else echo -e "\033[1;33mBelow ${RECOMMENDED_MB} MB - build with: colcon build --parallel-workers 1\033[0m" fi echo } [ "${1:-}" = "--status" ] && { show_status; exit 0; } [ "$(id -u)" -eq 0 ] || die "Must run with sudo: sudo bash $0" # ----------------------------- UNINSTALL ------------------------------------- if [ "${1:-}" = "--uninstall" ]; then say "Removing zram" systemctl disable --now robot-zram.service 2>/dev/null for d in /dev/zram*; do [ -b "$d" ] && swapoff "$d" 2>/dev/null; done rm -f "$ZRAM_UNIT" "$ZRAM_SCRIPT" systemctl daemon-reload ok "zram removed" say "Removing $SWAPFILE" swapoff "$SWAPFILE" 2>/dev/null sed -i "\|^$SWAPFILE |d" /etc/fstab rm -f "$SWAPFILE" ok "swap file removed" show_status exit 0 fi RAM_KB=$(awk '/MemTotal/{print $2}' /proc/meminfo) say "This Pi has $((RAM_KB/1024)) MB RAM and $(nproc) cores" # ----------------------------- ZRAM ------------------------------------------ if [ "$SWAP_MODE" = "both" ] || [ "$SWAP_MODE" = "zram" ]; then say "Setting up zram (compressed swap in RAM)" # On Ubuntu's Raspberry Pi kernel the zram module lives in the # linux-modules-extra package, which is not installed by default. # linux-modules-extra-raspi follows kernel upgrades, so zram still # loads after the next kernel update; the -$(uname -r) one is for now. if ! dpkg -s linux-modules-extra-raspi >/dev/null 2>&1 || ! modprobe zram 2>/dev/null; then warn "installing linux-modules-extra (zram lives there on Ubuntu's Pi kernel)" apt-get install -y linux-modules-extra-raspi "linux-modules-extra-$(uname -r)" >/dev/null 2>&1 fi if modprobe zram 2>/dev/null; then ZRAM_BYTES=$(( RAM_KB * 1024 * ZRAM_FACTOR )) cat > "$ZRAM_SCRIPT" </dev/null [ -b /dev/zram0 ] || cat /sys/class/zram-control/hot_add >/dev/null 2>&1 swapoff /dev/zram0 2>/dev/null echo 1 > /sys/block/zram0/reset 2>/dev/null sleep 1 echo lz4 > /sys/block/zram0/comp_algorithm 2>/dev/null echo $ZRAM_BYTES > /sys/block/zram0/disksize mkswap /dev/zram0 >/dev/null 2>&1 swapon -p 5 /dev/zram0 ZSCRIPT chmod +x "$ZRAM_SCRIPT" cat > "$ZRAM_UNIT" </dev/null 2>&1 systemctl restart robot-zram.service sleep 2 ZSIZE=$(awk '/zram/{print int($3/1024)}' /proc/swaps) [ -n "$ZSIZE" ] && ok "zram active: ${ZSIZE} MB" \ || warn "zram did not come up - check: systemctl status robot-zram" else warn "This kernel has no zram module - skipping zram, the swap file still helps" fi fi # ----------------------------- FILE SWAP ------------------------------------- if [ "$SWAP_MODE" = "both" ] || [ "$SWAP_MODE" = "file" ]; then say "Setting up a ${FILE_SWAP_MB} MB swap file at $SWAPFILE" swapoff "$SWAPFILE" 2>/dev/null rm -f "$SWAPFILE" FREE_MB=$(df -m / | awk 'NR==2{print $4}') [ "$FREE_MB" -lt $((FILE_SWAP_MB + 1000)) ] \ && die "Not enough free space on the SD card (${FREE_MB} MB free, need $((FILE_SWAP_MB + 1000)) MB)." fallocate -l "${FILE_SWAP_MB}M" "$SWAPFILE" 2>/dev/null \ || dd if=/dev/zero of="$SWAPFILE" bs=1M count="$FILE_SWAP_MB" status=none \ || die "Could not create $SWAPFILE" chmod 600 "$SWAPFILE" mkswap "$SWAPFILE" >/dev/null || die "mkswap failed" swapon -p 0 "$SWAPFILE" || die "swapon failed" grep -q "^$SWAPFILE " /etc/fstab || echo "$SWAPFILE none swap sw,pri=0 0 0" >> /etc/fstab ok "swap file active and listed in /etc/fstab" fi # ----------------------------- VERIFY ---------------------------------------- say "Result" show_status echo "Swap is active now and will come back automatically after a reboot." echo "Check it any time with: sudo bash setup_swap.sh --status" echo