17 responses to “DeviceKit-power latency control”

  1. Johannes Berg

    Something similar is required to tell the wireless hardware how deep it can go into powersaving and how much networking latency you expect: if you’re connected to an AP, that AP may buffer frames for you, and you can ask for them to be sent to you only after some time and shut down your radio in the meantime.

    Therefore, it would be useful to extend such a mechanism in some way to incorporate wireless network latency/performance. Thoughts? We (the wireless kernel developers) haven’t really figured this out yet either, but obviously are willing to listen to input on how you and others would want to handle this in userspace.

  2. baze

    sounds nice to improve battery life in various ways easily.
    (what has the icon to do with power? ;) why not use a battery and a plug together or something similar?)

  3. John Stowers

    Can someone please explain how all these DeviceKit-* implementations differ from HAL, why it is better, etc?

    A birds eye view kind of thing

  4. Johannes Berg


    Oh, so it’s just a typical case of Intel wireless not working with the community, as always. Why am I not surprised?

    On the other hand, there’s no such code in the kernel now either, so that must be somebody’s experimental code they never bothered to show on the linux wireless list. Not really surprising of Intel wireless either though.

  5. Johannes Berg


    First, apologies for missing that h!

    Can’t say I’m offended, in particular not by you (!), I’m just somewhat disappointed that we discussed the wireless power management aspect at OLS and nobody there was aware of pm-qos, not even the Intel folks who work on wireless. It seems like at least some of the pm-qos design was done without asking the users, which isn’t always the best idea…

  6. onox

    if I understand it correctly: the latency control thing is used to give the kernel some information about how much time it can let devices sleep? What’s the difference with a system that not this latency control thing?

  7. davidz

    Uhm, not sure we should be using your blog as a mailing list – any chance you can post this to devkit-devel; I have a few comments. Thanks!


  8. Priit Laes

    Hum.. I see that a bunch of use cases are about running some kind of server (sql server, cron scripts). Isn’t power latency control a bit overengineering in these cases, as how many serious admins are running desktop environment on a business-critical server machine?

  9. Frederik

    I’m not sure how this is all supposed to work. I hope this is not yet another daemon to run? I read on Planet GNOME work is being done to improve GNOME’s start up time. Then it would be a shame that new bloat is added again. That would be two steps forward and one backward.

  10. Tore

    Not everything you’ll want to do in order to conserve power when on battery has to do with latency. For example:

    – shutting down unused radios such as bluetooth or wlan
    – lowering display panel brightness
    – shortening time required for display panel to shut down
    – enabling automatic suspend-to-ram when inactive
    – avoiding running non-essential background tasks such as updatedb

    Do you plan for your system service to handle such things, or should that be left to something else, like for instance PPM?

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