Timer coalescing is a computer system energy-saving technique that reduces central processing unit (CPU) power consumption by reducing the precision of software timers used for synchronization of process wake-ups, minimizing the number of times the CPU is forced to perform the relatively power-costly operation of entering and exiting idle states.
Implementations of timer coalescing
- The Linux kernel gained support for deferrable timers in 2.6.22,23 and controllable "timer slack" for threads in 2.6.28 allowing timer coalescing.45
- Timer coalescing has been a feature of Microsoft Windows from Windows 7 onward.6
- Apple's XNU kernel based OS X gained support as of OS X Mavericks.78
- FreeBSD supports it since September 2010.9
See also
- Advanced Configuration and Power Interface (ACPI)
- Advanced Programmable Interrupt Controller (APIC)
- High Precision Event Timer (HPET)
- HLT (x86 instruction)
- Interrupt coalescing
- Programmable interval timer
- Time Stamp Counter (TSC)
References
Anderson, Nate (June 11, 2013). "How OS X "Mavericks" works its power-saving magic". Ars Technica. Retrieved 2014-03-22. https://arstechnica.com/apple/2013/06/how-os-x-mavericks-works-its-power-saving-magic/ ↩
"Linux Kernel 2 6 22". kernelnewbies.org. Retrieved 2014-03-22. http://kernelnewbies.org/Linux_2_6_22 ↩
"Add support for deferrable timers". 2007-05-08. Retrieved 2014-03-22. https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=6e453a67510a17f01b63835f18569e8c3939a38c ↩
"time(7) - Linux manual page". Man7.org. Retrieved 2014-03-24. http://man7.org/linux/man-pages/man7/time.7.html ↩
"prctl(2) - Linux manual page". Man7.org. Retrieved 2014-03-24. http://man7.org/linux/man-pages/man2/prctl.2.html ↩
"Windows Timer Coalescing". Microsoft. January 20, 2009. Retrieved 2009-04-21. http://www.microsoft.com/whdc/system/pnppwr/powermgmt/TimerCoal.mspx ↩
"OS X Mavericks - Advanced Technologies". Apple Inc. Retrieved 2014-03-22. https://www.apple.com/osx/preview/advanced-technologies.html ↩
"OS X Mavericks: Core Technologies Overview" (PDF). Apple, Inc. June 10, 2013. Archived from the original (PDF) on June 26, 2013. Retrieved 2013-06-10. https://web.archive.org/web/20130626042313/http://images.apple.com/osx/preview/docs/OSX_Mavericks_Core_Technology_Overview.pdf ↩
"Refactor timer management code". 13 September 2010. https://lists.freebsd.org/pipermail/svn-src-all/2010-September/028792.html ↩