Commit 0405d4bcded9c37e8d9e437a8d33987ee9591f69 - zram-tools

New release Jonathan Carter 1 year, 8 months ago

6 changed file(s) with 220 addition(s) and 0 deletion(s). Raw diff Collapse all Expand all

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COPYING less more

	0	Copyright (c) 2014-2019, Jonathan Carter <jcarter@linux.com>
	1
	2	Permission to use, copy, modify, and/or distribute this software for any
	3	purpose with or without fee is hereby granted, provided that the above
	4	copyright notice and this permission notice appear in all copies.
	5
	6	THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
	7	WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
	8	MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
	9	ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
	10	WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
	11	ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
	12	OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

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README.md less more

	0	zram-tools
	1	==========
	2
	3	Scripts for managing zram device, currently only for zramswap,
	4	but more tools could be implemented in the future, such as managing
	5	/tmp on zram.
	6
	7	zramswap start
	8	--------------
	9
	10	Sets up zram devices and initializes swap.
	11
	12	zramswap stop
	13	-------------
	14
	15	Removes all current zram swap space and device.
	16
	17	zramswap status
	18	---------------
	19
	20	Shows information on data stored in zram swap.
	21
	22	/etc/default/zramswap
	23	---------------------
	24
	25	Configuration file for zramswap.

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conf/zramswap less more

	0	# Compression algorithm selection
	1	# speed: lz4 > zstd > lzo
	2	# compression: zstd > lzo > lz4
	3	# This is not inclusive of all that is available in latest kernels
	4	# See /sys/block/zram0/comp_algorithm (when zram module is loaded) to see
	5	# what is currently set and available for your kernel[1]
	6	# [1] https://github.com/torvalds/linux/blob/master/Documentation/blockdev/zram.txt#L86
	7	#ALGO=lz4
	8
	9	# Specifies the amount of RAM that should be used for zram
	10	# based on a percentage the total amount of available memory
	11	# This takes precedence and overrides SIZE below
	12	#PERCENT=50
	13
	14	# Specifies a static amount of RAM that should be used for
	15	# the ZRAM devices, this is in MiB
	16	#SIZE=256
	17
	18	# Specifies the priority for the swap devices, see swapon(2)
	19	# for more details. Higher number = higher priority
	20	# This should probably be higher than hdd/ssd swaps.
	21	#PRIORITY=100

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zramswap less more

	0	#!/bin/bash
	1
	2	# This script does the following:
	3	# zramswap start:
	4	# Space is assigned to the zram device, then swap is initialized and enabled.
	5	# zramswap stop:
	6	# Somewhat potentially dangerous, removes zram module at the end
	7
	8	# https://github.com/torvalds/linux/blob/master/Documentation/blockdev/zram.txt
	9
	10	readonly CONFIG="/etc/default/zramswap"
	11	readonly SWAP_DEV="/dev/zram0"
	12
	13	if command -v logger >/dev/null; then
	14	function elog {
	15	logger -s "Error: $*"
	16	exit 1
	17	}
	18
	19	function wlog {
	20	logger -s "$*"
	21	}
	22	else
	23	function elog {
	24	echo "Error: $*"
	25	exit 1
	26	}
	27
	28	function wlog {
	29	echo "$*"
	30	}
	31	fi
	32
	33	function start {
	34	wlog "Starting Zram"
	35
	36	# Load config
	37	test -r "${CONFIG}" \|\| wlog "Cannot read config from ${CONFIG} continuing with defaults."
	38	source "${CONFIG}" 2>/dev/null
	39
	40	# Set defaults if not specified
	41	: "${ALGO:=lz4}" "${SIZE:=256}" "${PRIORITY:=100}"
	42
	43	SIZE=$((SIZE * 1024 * 1024)) # convert amount from MiB to bytes
	44
	45	# Prefer percent if it is set
	46	if [ -n "${PERCENT}" ]; then
	47	readonly TOTAL_MEMORY=$(awk '/MemTotal/{print $2}' /proc/meminfo) # in KiB
	48	readonly SIZE="$((TOTAL_MEMORY * 1024 * PERCENT / 100))"
	49	fi
	50
	51	modprobe zram \|\| elog "inserting the zram kernel module"
	52	echo -n "${ALGO}" > /sys/block/zram0/comp_algorithm \|\| elog "setting compression algo to ${ALGO}"
	53	echo -n "${SIZE}" > /sys/block/zram0/disksize \|\| elog "setting zram device size to ${SIZE}"
	54	mkswap "${SWAP_DEV}" \|\| elog "initialising swap device"
	55	swapon -p "${PRIORITY}" "${SWAP_DEV}" \|\| elog "enabling swap device"
	56	}
	57
	58	function status {
	59	test -x "$(which zramctl)" \|\| elog "install zramctl for this feature"
	60	test -b "${SWAP_DEV}" \|\| elog "${SWAP_DEV} doesn't exist"
	61	# old zramctl doesn't have --output-all
	62	#zramctl --output-all
	63	zramctl "${SWAP_DEV}"
	64	}
	65
	66	function stop {
	67	wlog "Stopping Zram"
	68	test -b "${SWAP_DEV}" \|\| wlog "${SWAP_DEV} doesn't exist"
	69	swapoff "${SWAP_DEV}" 2>/dev/null \|\| wlog "disabling swap device: ${SWAP_DEV}"
	70	modprobe -r zram \|\| elog "removing zram module from kernel"
	71	}
	72
	73	function usage {
	74	cat << EOF
	75
	76	Usage:
	77	zramswap (start\|stop\|restart\|status)
	78
	79	EOF
	80	}
	81
	82	case "$1" in
	83	start) start;;
	84	stop) stop;;
	85	restart) stop && start;;
	86	status) status;;
	87	"") usage;;
	88	*) elog "Unknown option $1";;
	89	esac

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zramswap.8 less more

	0	.TH "zramswap" 1 "2018-10-04" "zramswap"
	1	.SH NAME
	2	zramswap \- configure swap on zram
	3	.SH SYNOPSIS
	4	.B zramswap
	5	[OPTION]
	6	.SH DESCRIPTION
	7	zram is a Linux feature that allows a user to create compressed ramdisks.
	8
	9	zramswap sets up swap in zram, which effectively allows you to compress
	10	memory.
	11
	12	Common use cases:
	13
	14	On machines with low memory, mitigates the tedious situation where the
	15	machine is out of memory and then it starts swapping to disk only to lose
	16	a large amount of disk bandwidth.
	17
	18	On machines where the main swap file is on flash memory, zramswap may only
	19	provide marginal performance increase (especially on fast SSD media),
	20	however, it will prevent some amount of wear on your flash memory. zramswap
	21	is especially beneficial if your main flash is on SD/MMC/CF card.
	22
	23	On servers that run many virtual machines or containers, zramswap allows you to
	24	optimise memory usage by swapping out data that's not often accessed, but when
	25	a user needs to access it, it will be available fast. It allows you to
	26	overcommit on memory with a negligible hit on your application performance
	27	(and often an improvement in performance where you can use more main memory
	28	for filesystem cache).
	29
	30	.SH OPTIONS
	31	Usage: zramswap [OPTION]
	32
	33	.B ZRAMSWAP Options
	34
	35	\fB\ start\fR
	36	.RS
	37	Sets up zram swap.
	38	.RE
	39
	40	\fB\ stop\fR
	41	.RS
	42	Tears down zram swap.
	43	.RE
	44
	45	\fB\ status\fR
	46	.RS
	47	Displays zram swap usage and compression ratio.
	48	.RE
	49
	50	.SH REPORTING BUGS
	51	Please file issues at: https://salsa.debian.org/jcc/zram-tools/issues
	52
	53	.SH AUTHORS
	54	This manual page was written by Jonathan Carter <jcarter@linux.com>

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zramswap.service less more

	0	[Unit]
	1	Description=Linux zramswap setup
	2	Documentation=man:zramswap(8)
	3
	4	[Service]
	5	EnvironmentFile=-/etc/default/zramswap
	6	ExecStart=/usr/sbin/zramswap start
	7	ExecStop=/usr/sbin/zramswap stop
	8	ExecReload=/usr/sbin/zramswap restart
	9	Type=oneshot
	10	RemainAfterExit=true
	11
	12	[Install]
	13	WantedBy=multi-user.target