Research idle cycle injection versus hotplug

Registered by Michael Turquette

This blueprint is covered by subissues of the epic

Measure effectiveness of SMP CPUidle (without any forced idleness) versus algorithmic Hotplug Policy implementation versus Idle Cycle injection.

Blueprint information

Amit Kucheria
Michael Turquette
Daniel Lezcano
Series goal:
Accepted for trunk
Not started
Milestone target:
milestone icon backlog
Completed by
Serge Broslavsky

Related branches



These items will not be done as cpuoffline is not seen as a way to do power savings upstream.
[vincent-guittot] implement Ux500 support for CPUoffline: TODO
[amitdanielk] implement Samsung support for CPUoffline: TODO
[amitdanielk] analyze power savings with and without CPUoffline support: TODO

Idle injector info:

Comparative analysis on SMP CPUidle versus SMP CPUidle + hotplug:
Compare power savings on VDD_MPU using some benchmarks
Compare power savings on ~VBAT using some benchmarks

The item "forward port idle cycle injector patches to linaro-2.6.39: was BLOCKED", but in reality it will never happen. Google has decided to drop these patches and not support them publicly.

[daniel-lezcano, 2013-01-15] Intel has posted a patch series for "Intel power clamp":
It is worth study the approach as it could fit our needs to 'sync' the cpus for idling a package.

[ototo, 2013-02-01] Moving unfinished items to 2013.02.

[daniel-lezcano, 2013-02-04] Study generic idle injection with the cpuidle driver to retrieve the cpuidle states.

[daniel-lezcano, 2013-03-12] As discussed at Connect with Amit, this is not a must-have right now, I changed the priority to undefined.


Work Items

Work items for 2011.07:
[mturquette] design cpuoffline framework: DONE
[mturquette] separate hotplug policy implementation from TI's cpufreq-hotplug governor: DONE
[mturquette] implement cpuoffline framework: DONE
[mturquette] implement OMAP4 support for cpuoffline framework: DONE
[mturquette] implement avg-load governor for cpuoffline framework: DONE
[mturquette] post cpuoffline patches to linux-pm list: DONE

Work items for 2011.08:
[mturquette] integrate review comments from list: DONE
[mturquette] Publish git tree with cpuoffline framework patches for integration: DONE
[mturquette] define relevant measurements to compare across implementations: DONE
[vincent-guittot] analyze power savings with and without CPUoffline support: DONE
[mturquette] compare "raw" SMP CPUidle on Panda with the separated hotplug policy; publish the results for further discussion: DONE

Work items for 2013.02:
[daniel-lezcano] study intel power clamp (idle injection) : DONE

Work items for 2013.03:
[daniel-lezcano] investigate with intel using the cpuidle driver instead of a probe function : TODO
[daniel-lezcano] find common code between ARM and Intel : TODO
[daniel-lezcano] write a idle injection for ARM : TODO

Dependency tree

* Blueprints in grey have been implemented.

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