Timer coalescing: Difference between revisions

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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.^[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]

References

^ Anderson, Nate (June 11, 2013). "How OS X "Mavericks" works its power-saving magic". Ars Technica. Retrieved 2014-03-22.
^ "Linux Kernel 2 6 22". kernelnewbies.org. Retrieved 2014-03-22.
^ "Add support for deferrable timers". 2007-05-08. Retrieved 2014-03-22.
^ "time(7) - Linux manual page". Man7.org. Retrieved 2014-03-24.
^ "prctl(2) - Linux manual page". Man7.org. Retrieved 2014-03-24.
^ "Windows Timer Coalescing". Microsoft. January 20, 2009. Retrieved 2009-04-21.
^ "OS X Mavericks - Advanced Technologies". Apple Inc. Retrieved 2014-03-22.
^ "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.
^ "Refactor timer management code". 13 September 2010.

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[ars_technica_os_x-1] Anderson, Nate (June 11, 2013). "How OS X "Mavericks" works its power-saving magic". Ars Technica. Retrieved 2014-03-22.

[k_newb-2] "Linux Kernel 2 6 22". kernelnewbies.org. Retrieved 2014-03-22.

[git_commit-3] "Add support for deferrable timers". 2007-05-08. Retrieved 2014-03-22.

[man_page:_time-4] "time(7) - Linux manual page". Man7.org. Retrieved 2014-03-24.

[man_page:_prctl-5] "prctl(2) - Linux manual page". Man7.org. Retrieved 2014-03-24.

[6] "Windows Timer Coalescing". Microsoft. January 20, 2009. Retrieved 2009-04-21.

[Advanced_Technologies-7] "OS X Mavericks - Advanced Technologies". Apple Inc. Retrieved 2014-03-22.

[OS_X_Mavericks:_Core_Technologies_Overview-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". 13 September 2010.

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@@ Line 1: / Line 1: @@
+{{Short description|Operating system feature to reduce CPU idle time}}
-'''Timer coalescing''' is an energy-saving technique that reduces [[processor power consumption]] by reducing the precision of [[software timer]]s 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 state]]s,
+'''Timer coalescing''' is a computer system [[power management|energy-saving]] technique that reduces [[central processing unit]] (CPU) power consumption by reducing the precision of [[software timer]]s 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 (CPU)|idle states]].<ref name=ars_technica_os_x/>
+== Implementations of timer coalescing ==
-Timer coalescing has been a feature of [[Microsoft Windows]] from [[Windows 7]] onward,<ref>{{cite web
+*The [[Linux kernel]] gained support for deferrable timers in 2.6.22,<ref name=k_newb/><ref name=git_commit/> and controllable "timer slack" for [[thread (computing)|thread]]s in 2.6.28 allowing timer coalescing.<ref name="man page: time"/><ref name="man page: prctl"/>
+*Timer coalescing has been a feature of [[Microsoft Windows]] from [[Windows 7]] onward.<ref>{{cite web
 |url=http://www.microsoft.com/whdc/system/pnppwr/powermgmt/TimerCoal.mspx
 |title=Windows Timer Coalescing
@@ Line 8: / Line 11: @@
 |publisher=Microsoft
 }}</ref>
-and in Apple's [[Mac OS X]] from [[Mac OS X Mavericks]].<ref name="Advanced Technologies">{{cite web|url=http://www.apple.com/osx/preview/advanced-technologies.html|title=OS X Mavericks - Advanced Technologies|publisher=Apple Inc.}}</ref><ref name="OS X Mavericks: Core Technologies Overview">{{cite web | title=OS X Mavericks: Core Technologies Overview | url=http://images.apple.com/osx/preview/docs/OSX_Mavericks_Core_Technology_Overview.pdf | publisher=Apple, Inc. | date=June 10, 2013 | accessdate=June 10, 2013 }}</ref>
+*[[Apple Inc.|Apple]]'s [[XNU]] kernel based [[OS X]] gained support as of [[OS X Mavericks]].<ref name="Advanced Technologies"/><ref name="OS X Mavericks: Core Technologies Overview"/>
+*[[FreeBSD]] supports it since September 2010.<ref>{{cite web|url=https://lists.freebsd.org/pipermail/svn-src-all/2010-September/028792.html
+|title=Refactor timer management code
-== References ==
+|date=13 September 2010
-{{reflist}}
+}}</ref>
 == See also ==
+{{Div col}}
-* [[CPU power management]]
+* [[Advanced Configuration and Power Interface]] (ACPI)
+* [[Advanced Programmable Interrupt Controller]] (APIC)
+* [[High Precision Event Timer]] (HPET)
+* [[HLT (x86 instruction)]]
 * [[Interrupt coalescing]]
-* [[Tickless kernel]]
+* [[Programmable interval timer]]
-* [[Performance per watt]]
+* [[Time Stamp Counter]] (TSC)
+{{Div col end}}
-* [[Low-power electronics]]
+== References ==
+{{reflist | 30em | refs=
+<ref name=ars_technica_os_x>
+  {{cite web | url = https://arstechnica.com/apple/2013/06/how-os-x-mavericks-works-its-power-saving-magic/
+  | title = How OS X "Mavericks" works its power-saving magic | author = Anderson, Nate | publisher = [[Ars Technica]]
+  | date = June 11, 2013 | accessdate=2014-03-22}}</ref>
+<ref name=git_commit>
+  {{cite web|url=https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=6e453a67510a17f01b63835f18569e8c3939a38c
+  | title = Add support for deferrable timers | date = 2007-05-08 | accessdate=2014-03-22}}</ref>
+<ref name=k_newb>
+  {{cite web|url=http://kernelnewbies.org/Linux_2_6_22|title=Linux Kernel 2 6 22|publisher=kernelnewbies.org|accessdate=2014-03-22}}</ref>
+<ref name="Advanced Technologies">
+  {{cite web|url=https://www.apple.com/osx/preview/advanced-technologies.html|title=OS X Mavericks - Advanced Technologies
+  |publisher=Apple Inc.|accessdate=2014-03-22}}</ref>
+<ref name="OS X Mavericks: Core Technologies Overview">
+  {{cite web
+ |title       = OS X Mavericks: Core Technologies Overview
+ |url         = https://images.apple.com/osx/preview/docs/OSX_Mavericks_Core_Technology_Overview.pdf
+ |publisher   = Apple, Inc.
+ |date        = June 10, 2013
+ |accessdate  = 2013-06-10
+ |url-status     = dead
+ |archiveurl  = https://web.archive.org/web/20130626042313/http://images.apple.com/osx/preview/docs/OSX_Mavericks_Core_Technology_Overview.pdf
+ |archivedate = June 26, 2013
+}}</ref>
+<ref name="man page: time">{{cite web|url=http://man7.org/linux/man-pages/man7/time.7.html |title=time(7) - Linux manual page |publisher=Man7.org |date= |accessdate=2014-03-24}}</ref>
+<ref name="man page: prctl">{{cite web|url=http://man7.org/linux/man-pages/man2/prctl.2.html |title=prctl(2) - Linux manual page |publisher=Man7.org |date= |accessdate=2014-03-24}}</ref>
+}}
 {{compsci-stub}}
+[[Category:Operating system kernels]]
+[[Category:Synchronization]]