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bustd is a lightweight process killer daemon for out-of-memory scenarios for Linux!

  • Features

Insignificant memory usage!

bustd seems to use less memory than some other lean daemons such as earlyoom.

Also quite insignificant CPU usage

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: https://sourceware.org/legacy-ml/libc-alpha/2015-08/msg00512.html (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.

bustd locks all pages mapped into its address space

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.

Checks for Pressure Stall Information

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.



Verified by

Verified on




Verified by

Merazi <merazi@tuta.io>

Verified on

9 July 2021

Leaders and contributors

Vinícious Miguel Bustd's Creator
José Luis (Chronos504)Contact

Resources and communication

Software prerequisites


"MIT" is not in the list (ACEL, AFL-3.0, AGPL-1.0, AGPL-1.0-or-later, AGPL-3.0, AGPL-3.0-or-later, AGPL-3.0-or-later-with-exception, AGPL-3.0-with-exception, AGPLv1orlater, AGPLv3, ...) of allowed values for the "License" property.

"Contact" is not in the list (Maintainer, Contributor, Developer, Sponsor, Unknown) of allowed values for the "Role" property.

"Bustd's Creator" is not in the list (Maintainer, Contributor, Developer, Sponsor, Unknown) of allowed values for the "Role" property.

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