Timer coalescing

Timer coalescing is a computer system energy-saving technique that reduces central processing unit (CPU) power consumption by reducing the precision of software timers to allow the 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.[1]

Implementations of timer coalescing

• The Linux kernel gained support for deferrable timers in 2.6.22,[2][3] and controllable "timer slack" for threads in 2.6.28 allowing timer coalescing.[4][5]
• 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.[7][8]
• 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

1. Anderson, Nate (June 11, 2013). "How OS X "Mavericks" works its power-saving magic". Ars Technica. Retrieved 2014-03-22.
2. "Linux Kernel 2 6 22". kernelnewbies.org. Retrieved 2014-03-22.
3. "Add support for deferrable timers". 2007-05-08. Retrieved 2014-03-22.
4. "time(7) - Linux manual page". Man7.org. Retrieved 2014-03-24.
5. "prctl(2) - Linux manual page". Man7.org. Retrieved 2014-03-24.
6. "Windows Timer Coalescing". Microsoft. January 20, 2009. Retrieved 2009-04-21.
7. "OS X Mavericks - Advanced Technologies". Apple Inc. Retrieved 2014-03-22.
8. "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.
9. "Refactor timer management code".