bustd
is a lightweight process killer daemon for out-of-memory scenarios for Linux!
bustd
seems to use less memory than some other lean daemons such as earlyoom
:
$ ps -F -C bustd
UID PID PPID C SZ RSS PSR STIME TTY TIME CMD
vrmiguel 353609 187407 5 151 8 2 01:20 pts/2 00:00:00 target/x86_64-unknown-linux-musl/release/bustd -V -n
$ ps -F -C earlyoom
UID PID PPID C SZ RSS PSR STIME TTY TIME CMD
vrmiguel 350497 9498 0 597 688 6 01:12 pts/1 00:00:00 ./earlyoom/
¹: RSS stands for resident set size and represents the portion of RAM occupied by a process.
²: Compared when bustd was in this commit and earlyoom in this one.
bustd
compiled with musl libc and earlyoom with glibc through GCC 11.1. Different configurations would likely change these figures.
Much like earlyoom
and nohang
, bustd
uses adaptive sleep times during its memory polling. Unlike these two, however, bustd
does not read from /proc/meminfo
, instead opting for the sysinfo
syscall.
This approach has its up- and downsides. The amount of free RAM that sysinfo
reads does not account for cached memory, while MemAvailable
in /proc/meminfo
does.
The sysinfo
syscall is one order of magnitude faster, at least according to this kernel patch (granted, from 2015).
As bustd
can't solely rely on the free RAM readings of sysinfo
, we check for memory stress through Pressure Stall Information.
Much like earlyoom
, bustd
uses mlockall
to avoid being sent to swap, which allows the daemon to remain responsive even when the system memory is under heavy load and susceptible to thrashing.
The Linux kernel, since version 4.20 (and built with CONFIG_PSI=y
), presents canonical new pressure metrics for memory, CPU, and IO.
In the words of Facebook Incubator:
PSI stats are like barometers that provide fair warning of impending resource
shortages, enabling you to take more proactive, granular, and nuanced steps
when resources start becoming scarce.
More specifically, bustd
checks for how long, in microseconds, processes have stalled in the last 10 seconds. By default, bustd
will kill a process when processes have stalled for 25 microseconds in the last ten seconds.
Available on the Arch User Repository
Available on the GURU project
Available on the Pop!_OS PPA (outdated)
Requirements:
- Rust toolchain
- Any C compiler
- Linux 4.20+ built with
CONFIG_PSI=y
git clone https://github.com/vrmiguel/bustd
cd bustd && cargo run --release
The -n, --no-daemon
flag is useful for running bustd
through an init system such as systemd
.
Binaries are generated at every commit through GitHub Actions
- Allow for customization of the critical scenario (PSI cutoff)
- Command-line argument for disabling daemonization (useful for runnning
bustd
as a systemd service) - Command-line argument to enable killing the entire process group, not just the chosen process itself
- Allow the user to setup a list of software that
bustd
should never kill - Notification sending and general notification customization settings