Hi! https://fedoraproject.org/wiki/Changes/ZRAMforARMimages is a change to automatically create a zram device on memory-constrained systems. It is implemented using 'zram' package, which uses a service unit and two bash scripts to implement the starting and stopping of the zram device. I wanted to explore an alternative approach, using a systemd generator [1], to create (or not) the unit to create the zram device. The advantages are: - lower footprint (a custom binary instead of a shell script using grep, awk, and whatnot) - completely invisible if the memory limits are not met, no "skipped" units - minimalistic: the unit just creates the device, but tells systemd-modules-load.service to actually load the module, and creates a .swap unit for the device, so it will be managed by systemd in the usual fashion. Systemd generators are often written in C, to keep them mean and lean, but C is not an attractive option for many people. We have wanted to explore the approach of writing generators in Rust. zram-generator doubles as a proof-of-concept and example of a simple-yet-not-trivial systemd generator in Rust. Without further ado: upstream project [2], fedora package review [3]. Many thanks to Igor Gnatenko and Martin Sehnoutka for reviews of the code. It works like this: 1. /usr/lib/systemd/zram-generator runs, checks if we have less memory than the limit 2. /run/modules-load.d/zram.conf is created to have "zram" module loaded 3. /run/systemd/generator/swap-create@zram0.service is created, it'll initialize /dev/zram0 4. /run/systemd/generator/dev-zram0.swap is created, and added to swap.target 5. swap.target is pulled in by systemd, the config from items 2, 3, 4 is executed. [1] https://www.freedesktop.org/software/systemd/man/systemd.generator.html [2] https://github.com/systemd/zram-generator [3] https://bugzilla.redhat.com/show_bug.cgi?id=1622127 Comments, ideas, reviews of the package, etc, are very much welcome. I think this might be used to replace the 'zram' package, but it's too early to say. Zbyszek _______________________________________________ devel mailing list -- devel@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://getfedora.org/code-of-conduct.html List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@xxxxxxxxxxxxxxxxxxxxxxx/message/PCP7YAF7LBF5MLI36XWYNISQCYIDRNHS/
