[xorcist]

  man ulimit

Not sure what constitutes a regular Linux system but apart from the shell command the underlying ulimit syscall getrlimit(2) is in the kernel itself. One can set hard and soft limits on a per process granularity.

Normally each service has a dedicated uid and limits as well as nice levels are set in /etc/security/limits.conf which is read on login sessions by pam_limits.

This is in every bsd- and posix-like system and some of the soft limits have standardised signals assigned to them. The man page has all the details and is easy enough to understand.

[cranekam]

ulimit on Linux doesn’t support limiting RSS, only VSZ. I’d argue that limiting RSS — i.e., how much of the process in main memory — is more aligned with what someone wants than how big its virtual address space is, which can easily be distorted by e.g. mmap()ing a huge file in.

IME trying to restrict by VSZ just leads to surprises when malloc() fails at surprising times. cgroups are a much better way to go.