pmaports/main/postmarketos-base/rootfs-etc-conf.d-zram-init

. /usr/share/misc/source_deviceinfo

# Size defaults to:
# - 75% of RAM for devices with 2GB of RAM or less
# - 50% of RAM for devices with between 2GB and 6GB of RAM
# - 25% of RAM for devices with greater 6GB of RAM
# This is loosely based on some data here:
# https://gitlab.com/postmarketOS/pmaports/-/merge_requests/3752#note_1229631449

_mem_size_mb="$(LC_ALL=C free -m | awk '/^Mem:/{print $2}')"

if [ $_mem_size_mb -le 2048 ]; then
        _size_pct=75
elif [ $_mem_size_mb -gt 6144 ]; then
        _size_pct=25
else
        _size_pct=50
fi

# Allow overriding the size as a percentage of RAM using a deviceinfo var, or
# disabling it completely
if [ -n "$deviceinfo_zram_swap_pct" ]; then

        # 0% --> disable zram swap
        if [ "$deviceinfo_zram_swap_pct" == "0" ]; then
                echo "zram swap: disabled in deviceinfo, exiting"
                exit 0
        fi

        _size_pct="$deviceinfo_zram_swap_pct"
fi

size0=$(($_mem_size_mb * $_size_pct / 100))

echo "zram swap: activating with size: $size0 MB"
# zstd (since linux-4.18), lz4 (since linux-3.15), or lzo.
# Size: zstd (best) > lzo > lz4. Speed: lz4 (best) > zstd > lzo
algo0=zstd 

# The following are defaults from the zram-init package:
load_on_start=yes
unload_on_stop=yes
num_devices=1
type0=swap
flag0= # The default "16383" is fine for us
mlim0= # no hard memory limit
back0= # no backup device
icmp0= # no incompressible page writing to backup device
idle0= # no idle page writing to backup device
wlim0= # no writeback_limit for idle page writing for backup device
notr0= # keep the default on linux-3.15 or newer
maxs0=1 # maximum number of parallel processes for this device
labl0=zram_swap # the label name
uuid0= # Do not force UUID
args0= # we could e.g. have set args0="-L 'zram_swap'" instead of using labl0