raspbiantools: Add option to enable compressed memory (ZRAM)

Compressed memory (ZRAM) can be used with low memory embedded devices. ZRAM has compression ratio of up to 4:1 if zstd algorithm is used. 256MB
 of reserved physical memory can store up to 1024MB. It is only used if free memory is getting low. It is much faster than disk swapping. It also prevents linux from using disk swap until ZRAM is full.
https://wiki.debian.org/ZRam
https://wiki.ubuntuusers.de/zRam/
https://haydenjames.io/raspberry-pi-performance-add-zram-kernel-parameters/

Add an option which enables ZRAM with a swap size of 50% of physical memory size.

Example: Raspberry Pi4, 2GB, RetroPie 4.8

Meminfo without ZRAM
pi@retropie:~ $ cat /proc/meminfo
MemTotal:        1917108 kB
MemFree:         1567396 kB
MemAvailable:    1759312 kB
Buffers:           24592 kB
Cached:           240928 kB
SwapCached:            0 kB
Active:           115120 kB
Inactive:         170404 kB
Active(anon):        616 kB
Inactive(anon):    29056 kB
Active(file):     114504 kB
Inactive(file):   141348 kB
Unevictable:          16 kB
Mlocked:              16 kB
HighTotal:       1232896 kB
HighFree:         959980 kB
LowTotal:         684212 kB
LowFree:          607416 kB
SwapTotal:        102396 kB
SwapFree:         102396 kB
Dirty:             30800 kB
Writeback:             0 kB
AnonPages:         20052 kB
Mapped:            32344 kB
Shmem:              9668 kB
KReclaimable:      18456 kB
Slab:              35056 kB
SReclaimable:      18456 kB
SUnreclaim:        16600 kB
KernelStack:        1136 kB
PageTables:         1796 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:     1060948 kB
Committed_AS:     112832 kB
VmallocTotal:     245760 kB
VmallocUsed:        5208 kB
VmallocChunk:          0 kB
Percpu:              576 kB
CmaTotal:         327680 kB
CmaFree:          313280 kB

Meminfo with 50% ZRAM
pi@retropie:~ $ cat /proc/meminfo
MemTotal:        1917108 kB
MemFree:         1604616 kB
MemAvailable:    1676408 kB
Buffers:           20880 kB
Cached:           152212 kB
SwapCached:            0 kB
Active:            45144 kB
Inactive:         149896 kB
Active(anon):        632 kB
Inactive(anon):    55996 kB
Active(file):      44512 kB
Inactive(file):    93900 kB
Unevictable:       25004 kB
Mlocked:              16 kB
HighTotal:       1232896 kB
HighFree:        1020208 kB
LowTotal:         684212 kB
LowFree:          584408 kB
SwapTotal:       1060940 kB
SwapFree:        1060940 kB
Dirty:                72 kB
Writeback:             0 kB
AnonPages:         46988 kB
Mapped:            70232 kB
Shmem:             34672 kB
KReclaimable:      13088 kB
Slab:              28820 kB
SReclaimable:      13088 kB
SUnreclaim:        15732 kB
KernelStack:        1248 kB
PageTables:         2124 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:     2019492 kB
Committed_AS:     177464 kB
VmallocTotal:     245760 kB
VmallocUsed:        7412 kB
VmallocChunk:          0 kB
Percpu:              576 kB
CmaTotal:         327680 kB
CmaFree:          283624 kB

Author: gizmo98

scriptmodules/supplementary/raspbiantools.sh

@@ -125,15 +125,46 @@ function enable_modules_raspbiantools() {
     done
 }
 
+function enable_zram_raspbiantools() {
+    if [[ "$__os_id" == "Raspbian" ]] || [[ "$__os_id" == "Debian" ]]; then
+        aptInstall zram-tools
+        # Use 50% of the current memory for ZRAM
+        local percent="50"
+        iniConfig "=" "" "/etc/default/zramswap"
+        # Raspbian Buster uses keyword PERCENTAGE
+        iniSet "PERCENTAGE" "$percent"
+        # Debian Bullseye/Bookworm use keyword PERCENT
+        iniSet "PERCENT" "$percent"
+        # Use zstd compression algorithm if kernel supports it
+        [[ -f /sys/class/block/zram0/comp_algorithm ]] && [[ "$(cat /sys/class/block/zram0/comp_algorithm)" == *zstd* ]] && iniSet "ALGO" "zstd"
+        service zramswap stop
+        service zramswap start
+    elif [[ "$__os_id" == "Ubuntu" ]]; then
+        aptInstall zram-config
+        # Ubuntu has a automatic zram configuration
+    fi
+}
+
+function disable_zram_raspbiantools() {
+    if [[ "$__os_id" == "Raspbian" ]] || [[ "$__os_id" == "Debian" ]]; then
+        apt remove -y zram-tools
+    elif [[ "$__os_id" == "Ubuntu" ]]; then
+        apt remove -y zram-config
+    fi
+}
+
 function gui_raspbiantools() {
     while true; do
+        local zram_status="Enable"
+        [[ $(cat /proc/swaps) == *zram* ]] && zram_status="Disable"
         local cmd=(dialog --backtitle "$__backtitle" --menu "Choose an option" 22 76 16)
         local options=(
             1 "Upgrade Raspbian packages"
             2 "Install Pixel desktop environment"
             3 "Remove some unneeded packages (pulseaudio / cups / wolfram)"
             4 "Disable screen blanker"
             5 "Enable needed kernel module uinput"
+            6 "$zram_status compressed memory (ZRAM)"
         )
         local choice=$("${cmd[@]}" "${options[@]}" 2>&1 >/dev/tty)
         if [[ -n "$choice" ]]; then
@@ -155,6 +186,9 @@ function gui_raspbiantools() {
                 5)
                     rp_callModule "$md_id" enable_modules
                     ;;
+                6)
+                    [[ "$zram_status" == "Enable" ]] && rp_callModule "$md_id" enable_zram || rp_callModule "$md_id" disable_zram
+                    ;;
             esac
         else
             break