[avidiax]

SIGSTOP and SIGCONT are very useful as well.

SIGSTOP is the equivalent of Ctrl-Z in a shell, but you can address it to any process. If you have a server being bogged down, you can stop the offending process temporarily.

SIGCONT undoes SIGSTOP.

The cpulimit tool does this in an automated way so that a process can be limited to use x% of CPU. Nice/renice doesn't keep your CPU from hitting 100% even with an idle priority process, which may be undesirable if it drains battery quickly or makes the cooling fan loud.

[sunshowers]

Note Ctrl-Z is actually SIGTSTP, which is basically "SIGSTOP except the process can install a signal handler for it".

I have a very exciting blog post about debugging a nasty bug with how SIGTSTP works, coming very soon.