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LWN.net Weekly Edition for May 16, 2013
A look at the PyPy 2.0 release
PostgreSQL 9.3 beta: Federated databases and more
LWN.net Weekly Edition for May 9, 2013
(Nearly) full tickless operation in 3.10
This sounds like a job for a simple userspace program to me.
A single power preference knob
Posted Jun 24, 2010 8:48 UTC (Thu) by riteshsarraf (subscriber, #11138)
What I did not see in the RFC is is whether the switch from one profile to another is going to be adaptive or event driven.
In laptop-mode-tools, we do this based on events. Currently, ON_BAT and ON_AC.
Posted Jun 24, 2010 12:49 UTC (Thu) by nescafe (subscriber, #45063)
Posted Jun 24, 2010 12:21 UTC (Thu) by kov (subscriber, #7423)
Posted Jun 24, 2010 12:24 UTC (Thu) by NRArnot (subscriber, #3033)
9 byte comments not allowed you say?
Posted Jun 24, 2010 16:09 UTC (Thu) by ccurtis (guest, #49713)
Now, if only LWN had an optional "private reply" checkbox on the comment form...
Posted Jun 24, 2010 13:05 UTC (Thu) by Tobu (subscriber, #24111)
I agree that the kernel shouldn't contain complex policy, and should give ultimate control over policy to userland. But apparently the settings to tweak range wide and userland is missing some.
This master knob could provide a default value for settings that have yet to be tweaked by userland. When switching modes, the userland tweaks the master knob, then whatever knobs it is aware of. The problem with this is that most driver settings don't have an unset, please fall back to the default value. As a consequence, with the current proposal the default value can only be read by drivers that don't expose settings to userland yet. To be effective with existing, exposed settings, the master trigger would have to trigger changes to every one of them, and that's not something that should be done in-kernel.
Other solutions to the breadth of settings would be:
I like the introspection approach myself, since it will lead to better userland tools. Those tools should be able to discover and tweak settings they don't know about, and expose them to the user. It would also provide a good platform for experimenting with a watt meter.
Posted Jun 24, 2010 16:51 UTC (Thu) by nescafe (subscriber, #45063)
Posted Jun 24, 2010 23:04 UTC (Thu) by hummassa (subscriber, #307)
Posted Jun 25, 2010 1:20 UTC (Fri) by nescafe (subscriber, #45063)
Posted Jun 25, 2010 0:12 UTC (Fri) by Tobu (subscriber, #24111)
Hopefully the userland can figure out a value from the introspection. If the knob exposes a range with two examples, a powersave value and a balanced value, the userland can pick the powersave value for powersave and more energy-efficient modes, and the balanced value for balanced and more performance-oriented modes. Generally: pick the example nearest the desired mode.
If you have a more advanced user willing to figure things out, you can let them view the range, pick values and submit a patch, but that doesn't need to be the default user experience.
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