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#!/bin/sh /etc/rc.common
START=15
extra_command "compact" "Trigger compaction for all zram swap devices"
extra_command "status" "Print out information & statistics about zram swap devices"
ram_getsize()
{
local line
while read line; do case "$line" in MemTotal:*) set $line; echo "$2"; break ;; esac; done </proc/meminfo
}
zram_getsize() # in megabytes
{
local zram_size="$( uci -q get system.@system[0].zram_size_mb )"
local ram_size="$( ram_getsize )"
if [ -z "$zram_size" ]; then
# e.g. 6mb for 16mb-routers or 61mb for 128mb-routers
echo $(( ram_size / 2048 ))
else
echo "$zram_size"
fi
}
zram_dev()
{
local idx="$1"
echo "/dev/zram${idx:-0}"
}
zram_reset()
{
local dev="$1"
local message="$2"
local proc_entry="/sys/block/$( basename "$dev" )/reset"
logger -s -t zram_reset -p daemon.debug "$message via $proc_entry"
echo "1" >"$proc_entry"
}
zram_getdev()
{
#get unallocated zram dev
local zdev=$( zram_dev )
if [ "$(mount | grep $zdev)" ]; then
local idx=$(cat /sys/class/zram-control/hot_add)
zdev="$( zram_dev $idx )"
fi
echo $zdev
}
zram_comp_algo()
{
local dev="$1"
local zram_comp_algo="$( uci -q get system.@system[0].zram_comp_algo )"
if [ -z "$zram_comp_algo" ]; then
# default to lzo, which is always available
zram_comp_algo="lzo"
fi
if [ $(grep -c "$zram_comp_algo" /sys/block/$( basename $dev )/comp_algorithm) -ne 0 ]; then
logger -s -t zram_comp_algo -p daemon.debug "set compression algorithm '$zram_comp_algo' for zram '$dev'"
echo $zram_comp_algo > "/sys/block/$( basename $dev )/comp_algorithm"
else
logger -s -t zram_comp_algo -p daemon.debug "compression algorithm '$zram_comp_algo' is not supported for '$dev'"
fi
}
#print various stats info about zram swap device
zram_stats()
{
local zdev="/sys/block/$( basename "$1" )"
printf "\nGathering stats info for zram device \"$( basename "$1" )\"\n\n"
printf "ZRAM\n----\n"
printf "%-25s - %s\n" "Block device" $zdev
awk '{ printf "%-25s - %d MiB\n", "Device size", $1/1024/1024 }' <$zdev/disksize
printf "%-25s - %s\n" "Compression algo" "$(cat $zdev/comp_algorithm)"
awk 'BEGIN { fmt = "%-25s - %.2f %s\n"
fmt2 = "%-25s - %d\n"
print "\nDATA\n----" }
{ printf fmt, "Original data size", $1/1024/1024, "MiB"
printf fmt, "Compressed data size", $2/1024/1024, "MiB"
printf fmt, "Compress ratio", $1/$2, ""
print "\nMEMORY\n------"
printf fmt, "Memory used, total", $3/1024/1024, "MiB"
printf fmt, "Allocator overhead", ($3-$2)/1024/1024, "MiB"
printf fmt, "Allocator efficiency", $2/$3*100, "%"
printf fmt, "Maximum memory ever used", $5/1024/1024, "MiB"
printf fmt, "Memory limit", $4/1024/1024, "MiB"
print "\nPAGES\n-----"
printf fmt2, "Same pages count", $6
printf fmt2, "Pages compacted", $7 }' <$zdev/mm_stat
awk '{ printf "%-25s - %d\n", "Free pages discarded", $4 }' <$zdev/io_stat
}
zram_compact()
{
# compact zram device (reduce memory allocation overhead)
local zdev="/sys/block/$( basename "$1" )"
local old_mem_used=$(awk '{print $3}' <$zdev/mm_stat)
local old_overhead=$(awk '{print $3-$2}' <$zdev/mm_stat)
echo 1 > $zdev/compact
# If not running interactively, than just return
[ -z "$PS1" ] && return 0
echo ""
echo "Compacting zram device $zdev"
awk -v old_mem="$old_mem_used" -v ovr="$old_overhead" 'BEGIN { fmt = "%-25s - %.1f %s\n" }
{ printf fmt, "Memory usage reduced by ", (old_mem-$3)/1024/1024, "MiB"
printf fmt, "Overhead reduced by", (ovr-($3-$2))/ovr*100, "%" }' <$zdev/mm_stat
}
start()
{
[ -e /proc/swaps ] || {
logger -s -t zram_start -p daemon.crit "kernel doesn't support swap"
return 1
}
if [ $( grep -cs zram /proc/swaps ) -ne 0 ]; then
logger -s -t zram_start -p daemon.notice "zram swap is already mounted"
return 1
fi
local zram_dev="$( zram_getdev )"
[ -e "$zram_dev" ] || {
logger -s -t zram_start -p daemon.crit "[ERROR] device '$zram_dev' not found"
return 1
}
local zram_size="$( zram_getsize )"
local zram_priority="$( uci -q get system.@system[0].zram_priority )"
if [ -z "$zram_priority" ]; then
zram_priority="100"
fi
logger -s -t zram_start -p daemon.debug "activating '$zram_dev' for swapping ($zram_size MiB)"
zram_reset "$zram_dev" "enforcing defaults"
zram_comp_algo "$zram_dev"
echo $(( $zram_size * 1024 * 1024 )) >"/sys/block/$( basename "$zram_dev" )/disksize"
busybox mkswap "$zram_dev"
busybox swapon -d -p $zram_priority "$zram_dev"
}
stop()
{
local zram_dev
for zram_dev in $( grep zram /proc/swaps |awk '{print $1}' ); do {
logger -s -t zram_stop -p daemon.debug "deactivate swap $zram_dev"
busybox swapoff "$zram_dev" && zram_reset "$zram_dev" "claiming memory back"
local dev_index="$( echo $zram_dev | grep -o "[0-9]*$" )"
if [ $dev_index -ne 0 ]; then
logger -s -t zram_stop -p daemon.debug "removing zram $zram_dev"
echo $dev_index > /sys/class/zram-control/hot_remove
fi
} done
}
# show memory stats for all zram swaps
status()
{
for zram_dev in $( grep zram /proc/swaps |awk '{print $1}' ); do {
zram_stats "$zram_dev"
} done
}
# trigger compaction for all zram swaps
compact()
{
for zram_dev in $( grep zram /proc/swaps |awk '{print $1}' ); do {
zram_compact "$zram_dev"
} done
}
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