Tickless kernel explained

A tickless kernel is an operating system kernel in which timer interrupts do not occur at regular intervals, but are only delivered as required.^[1]

The Linux kernel on s390 from 2.6.6^[2] and on i386 from release 2.6.21^[3] can be configured to turn the timer tick off (tickless or dynamic tick) for idle CPUs using CONFIG_NO_HZ, and from 3.10 with CONFIG_NO_HZ_IDLE extended for non-idle processors with CONFIG_NO_HZ_FULL.^[4] The XNU kernel from Mac OS X 10.4 on, and the NT kernel from Windows 8 on, are also tickless.^[1] The Solaris 8 kernel introduced the cyclic subsystem which allows arbitrary resolution timers and tickless operation.^[5] FreeBSD 9 introduced a "dynamic tick mode" (aka tickless).^[6]

As of 2020, there is a plan to add this to MINIX 3^[7] in the medium term.^[8]

Notes and References

1. Web site: Better on the inside: under the hood of Windows 8. section "Tick tock". Peter. Bright. Ars Technica. October 28, 2012.
2. Web site: Linux 2.6.6-rc3 . Lwn.net . 2015-04-09.
3. Web site: Clockevents and dyntick . Lwn.net . 2007-02-21 . 2015-04-09.
4. Web site: (Nearly) full tickless operation in 3.10 . Lwn.net . 2015-04-09.
5. Web site: Bryan Cantrill (former Solaris kernel engineer) comment . 2017-01-07. .
6. Web site: What's cooking for FreeBSD 9?.
7. Web site: Tickless Kernel . 25 February 2020.
8. Web site: The MINIX 3 Road Map . 25 February 2020.