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Mobile/Powersaving: Difference between revisions
→OS-level process control
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== Metrics == | == Metrics == | ||
* # of wakeups/second, that prevent the CPU from sleeping. See [http://www.lesswatts.org/projects/powertop/ powertop]. Relevant in low CPU load. | * N900 - use [http://www.mauve.plus.com/bat.tar.gz this useful tool], run ././bq27220.sh -r | ||
* # of wakeups/second, that prevent the CPU from sleeping. See [http://www.lesswatts.org/projects/powertop/ powertop]. Relevant in low CPU load. See [[Mobile/Powersaving/Wakeups]] | |||
* CPU %. Relevant in high CPU load. | * CPU %. Relevant in high CPU load. | ||
* Disk usage (tools: iostat, atop). | * Disk usage (tools: iostat, atop). | ||
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== Ideas == | == Ideas == | ||
=== OS-level hinting === | |||
Different OSes have different application lifecycles. Depending on application states, we might want to do certain things. Information on different OSes is tracked [[Mobile/PowerManagement|here]]. | |||
=== OS-level process control === | === OS-level process control === | ||
The 'nuclear option': Use OS-level operations to make processes | The 'nuclear option': Use OS-level operations to make processes use low CPU % when they should. On Linux this can be done with SIG_STOP, SIG_CONT (see e.g. [http://cpulimit.sourceforge.net/ cpulimit]). Note that we are **not** completely freezing the process, that would be too bug-prone. | ||
'''Tracked in {{bug|568054}}''' | '''Tracked in {{bug|568054}}''' | ||
'''Uses''': | '''Uses''': | ||
* Force plugins to use low CPU % (Flash etc.) | * Force plugins to use low CPU % (Flash etc.) | ||
* Throttle all tabs when battery is low (kind of like laptops dim their monitors on low battery). | * Throttle all tabs when battery is low (kind of like laptops dim their monitors on low battery). | ||
** User-controllable speed setting, to save power by throttling? | ** User-controllable speed setting, to save power by throttling? | ||
'''Availability''': Probably Meego. Android lacks it in the Java API (but other signals are present, so perhaps it will be added), perhaps using the NDK it is possible though? | '''Availability''': Probably Meego. Android lacks it in the Java API (but other signals are present, so perhaps it will be added), perhaps using the NDK it is possible though? | ||
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A more messy option: Add separate options throughout our codebase to allow things to be temporarily frozen - JavaScript, animations, plugins, etc. etc. | A more messy option: Add separate options throughout our codebase to allow things to be temporarily frozen - JavaScript, animations, plugins, etc. etc. | ||
=== Platform-specific control === | |||
* On Android, processes have a [http://developer.android.com/guide/topics/fundamentals.html#lcycles lifecycle]. We currently pause the main thread - but no others - when we get OnPause. | |||
** Should we do more in OnStop? | |||
* Need to investigate other OSes | |||
== Tests == | == Tests == | ||
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** [http://www.webhamster.com/ Hamster dance] | ** [http://www.webhamster.com/ Hamster dance] | ||
** [http://www.cnn.com/ CNN] (takes 100% CPU in fennec for no user-apparent reason) | ** [http://www.cnn.com/ CNN] (takes 100% CPU in fennec for no user-apparent reason) | ||
* [[N900 tests]] | |||
== Bugs == | == Bugs == | ||
* {{bug|446418}} + dependencies - Investigate power management issues | * {{bug|446418}} + dependencies - Investigate power management issues | ||
* {{bug|567339}} - Excessive wake-ups after visiting start page | * {{bug|567339}} - Excessive wake-ups after visiting start page | ||