zram swap support for the PBP; aka: "how to download more RAM"

Code:

# zram-swap

Simple zram swap setup + teardown script for modern systemd Linux systems



https://github.com/foundObjects/zram-swap



### Why?



There are dozens of zram swap scripts out there, but most of them are overly

complicated and do things that haven't been neccessary since linux 3.X or have

massive logic errors in their swap size calculations. This script is simple and

reliable, modern and easy to configure.



### Installation



```

git clone https://github.com/foundObjects/zram-swap.git

cd zram-swap && sudo ./install.sh

```



### Usage



zram-swap.service will be started automatically after installation and during

each subsequent boot. The default allocation creates a zram device that should

use around half of physical memory when completely full.



The default configuration using lz4 should work well for most people. lzo may

provide slightly better RAM utilization at a cost of slightly more expensive

decompression. zstd should provide better compression than lz* and still be

moderately fast on most machines. On very modern kernels the best overall

choice is probably lzo-rle.



Edit `/etc/default/zram-swap` if you'd like to change compression algorithms or

swap allocation and then restart zram-swap with `systemctl restart

zram-swap.service`.



Run `zramctl` during use to monitor swap compression and real memory usage.



### Debugging



Start zram-swap.sh with `zram-swap.sh -x (start|stop)` to view the debug trace

and determine what's going wrong.



To dump the full execution trace during service start/stop edit

`/etc/systemd/systemd/zram-swap.service` and add -x to the following two lines:



```

ExecStart=/usr/local/sbin/zram-swap.sh -x init

ExecStop=/usr/local/sbin/zram-swap.sh -x  end

```



### Compatibility



This should run on pretty much any recent (4.0+? kernel) Linux system using

systemd. If anyone wants to try it on something really old and let me know how

far back compatibility goes I'm interested, but I don't have any legacy systems

to test on at the moment.



The script will also work on non-systemd Linux without issue and I welcome PRs

supporting SysVinit.

Code:

pkgname=zram-swap-git

_pkgname=zram-swap

pkgver=01a.r0.gd70751d

pkgrel=1

pkgdesc="A simple zram swap service for modern systemd Linux"

arch=('any')

url="https://github.com/foundObjects/zram-swap.git"

license=('MIT')

depends=('systemd' 'bash')

backup=('etc/default/zram-swap')

source=('git+https://github.com/foundObjects/zram-swap.git')

sha512sums=('SKIP')



pkgver() {

 cd ${_pkgname}

 git describe --long | sed 's/^v//;s/\([^-]*-g\)/r\1/;s/-/./g'

}



prepare() {

 cd ${_pkgname}

 sed -i 's/local\/sbin/bin/g' ./service/zram-swap.service

}



package() {

 cd ${_pkgname}

 install -Dm0644 "$srcdir/${_pkgname}"/service/zram-swap.service "$pkgdir"/usr/lib/systemd/system/zram-swap.service

 install -Dm0644 "$srcdir/${_pkgname}"/service/zram-swap.config "$pkgdir"/etc/default/zram-swap

 install -Dm0755 "$srcdir/${_pkgname}"/zram-swap.sh "$pkgdir"/usr/bin/zram-swap.sh

}