compress ram in debian and ubuntu

1. #!/bin/bash
### BEGIN INIT INFO
# Provides: zram
# Required-Start:
# Required-Stop:
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description: Increased Performance In Linux With zRam (Virtual Swap
Compressed in RAM)
# Description: Adapted from systemd scripts at
https://github.com/mystilleef/FedoraZram
### END INIT INFO
DEFAULTS="/etc/default/zram"
# Include defaults if available
[ -r "$DEFAULTS" ] && . "$DEFAULTS"
# Get lsb functions
. /lib/lsb/init-functions
start() {
# Add support of defaults file parameter - ZRAM_NDEVS
if [ -z "$ZRAM_NDEVS" ] || [ "$ZRAM_NDEVS" -le "0" ]; then
# get the number of CPUs
num_cpus=$(grep -c processor /proc/cpuinfo)
else
# or just use user specified
num_cpus=$ZRAM_NDEVS
fi
# if something goes wrong, assume we have 1
[ "$num_cpus" != 0 ] || num_cpus=1
decr_num_cpus=$((num_cpus - 1))
# find module and it's param name
error_file=$(mktemp ${RC_NAME}XXXXXX) # storage for error message
param_name=$(/usr/bin/env modinfo --parameters zram 2>$error_file | head -1
| cut -d: -f1)
error_message=$(<$error_file)
rm -f $error_file
mod_found=$?
# load dependency modules
if [ "$mod_found" == 0 ]; then
log_begin_msg "Loading zRAM kernel module"
modprobe zram "$param_name=$num_cpus"
log_end_msg $?
else
log_failure_msg "Failed to load zRAM kernel module: ${error_message}"
# shit happens, yep.
exit $mod_found
fi
# get the amount of memory in the machine
mem_total_kb=$(fgrep MemTotal /proc/meminfo | grep -E --only-matching
'[[:digit:]]+')
mem_total=$((mem_total_kb * 1024))
# Add support of defaults file parameter - ZRAM_USE_PERCENT
if [ -z "$ZRAM_USE_PERCENT" ] || [ "$ZRAM_USE_PERCENT" -le "0" ] ||

2. [ "$ZRAM_USE_PERCENT" -gt "100" ]; then
# use 100% of ram for zRAM storage (suitable for low-ram laptops)
use_percent=100
else
# or just use user specified
use_percent=$ZRAM_USE_PERCENT
fi
zsize=$((use_percent * mem_total / num_cpus / 100))
# initialize the devices
for i in $(seq 0 $decr_num_cpus); do
echo $zsize > /sys/block/zram$i/disksize
done
# get page size
page_size=$(/usr/bin/env getconf PAGESIZE || /usr/bin/env getconf PAGE_SIZE)
# Creating swap filesystems
for i in $(seq 0 $decr_num_cpus); do
msg="> Making swap on /dev/zram$i"
mkswap -p $page_size /dev/zram$i 2>&1 >/dev/null
[ "$?" -eq "0" ] && log_success_msg $msg || log_failure_msg $msg
done
# Switch the swaps on
for i in $(seq 0 $decr_num_cpus); do
msg=">> Activating swap on /dev/zram$i"
swapon -p 100 /dev/zram$i
[ "$?" -eq "0" ] && log_success_msg $msg || log_failure_msg $msg
done
# TODO FIXME need strict error reporting
# log_end_msg 0
}
stop() {
# Switching off swap ASAP
for zswap in $(fgrep /dev/zram /proc/swaps | cut -d' ' -f1); do
swapoff $zswap
done
# Custom kernels can contain zram compiled-in
[ -z "$(fgrep zram /proc/modules)" ] || rmmod zram
}
case "$1" in
start)
start
;;
stop)
stop
;;
restart)
stop
sleep 3
start
;;
*)
echo "Usage: $0 {start|stop|restart}"
RETVAL=1
esac