Request for feedback and/or participation on

Phil Knirsch pknirsch at
Wed Feb 4 16:41:36 UTC 2009

Eric Sandeen wrote:
> Phil Knirsch wrote:
>> Bill Nottingham wrote:
>>> Phil Knirsch (pknirsch at said: 
>>>> In case you're interested in helping make power management better in F11  
>>>>  feel free to participate in any form.
>>> I'd really like to find a way to get all the things listed in Documentation
>>> set up automatically for the user where appropriate - we should have
>>> all this stuff by default.
>>> Bill
>> Thats a good point Bill.
>> Of course most of the first points are things that the user just needs 
>> to do himself (power off his machine, choose the right dimension for the 
>> work he's doing etc).
>>  From the pure system ones i know that we at least already use the 
>> ondemand by default as soon as the CPU supports it, so we should be fine 
>> there.
>> Network card speeds and harddisk spindowns is a bit tricker imo, though 
>> we probably could enable a higher powersave mode for harddisk by default 
>> at least in case a user wants to save power. Some of this is/will be 
>> addressed by the tuned i'm working on which monitors the usage of 
>> network and harddisk devices and dynamically adapts the settings to the 
>> current use.
> See also:
> [Bug 454582] Tracker bug for over-eager apps that won't let disks spin down
> there are still some open bugs under that:
> Bug 454574 - mono writing to filesystem far too frequently
> Bug 457155 - Tomboy wakes up hard disk frecuently
> Bug 466601 - wpa_supplicant writing pointless(?) messages to log every 60s
> Bug 479192 - audit log written whenever cron wakes up, keeps disks spun up

Ah great. I've used the disknettop.stp i've written to start identifying 
some of those as well and have a few more for which i'll open BZs' in 
the next fw days. I'll just hook them up to the tracker bug then as well.

Would an overall tracker bug make sense for the whole power management 
changes we might be looking at?

>> Laptop mode and a higher value for dirty_writeback_centisecs, there i'm 
>> personally torn a bit myself. I personally do use it on all my machines 
>> (laptop and desktop), but i can understand people who are a bit paranoid 
>> about their data integrity not wanting to have that by default. But i'd 
>> personally be all for going that way.
>> In regard to relatime from what i've found so far we seem to be doing 
>> that already by default it seems, though i'd like to have that verified.
>> Then disabling CD-ROM polling is definitely something for the ServerSIG, 
>> but on a default Desktop i think the user experience would suffer if we 
>> would do that by default.
>> Enabling USB autosuspend looks like a good candidate for being a default 
>> though. I've used it on quite a few Fedora 10 machines around here and 
>> haven't experienced any problems so far, so it seems to have matured 
>> enough by now from what i can see.
>> Last but not least the dpms off, i think that should definitely be part 
>> of the Desktop screensaver defaults, especially if you look at how much 
>> power a modern LCD display eats when it's only dimmed down to black.
> Another one I'll add is powersave for audio hardware; I'll change the
> kernel default now (meant to do that last week and wandered off some
> other shiny thing instead).  There's some fear that it may cause
> clicks/pops on some hardware but we can get it in now and find out.

Ah yes, forgot to add those. You're refering to the hda_intel and ac97 
power_save settings, right?

Regards, Phil

Philipp Knirsch              | Tel.:  +49-711-96437-470
Team Lead Core Services      | Fax.:  +49-711-96437-111
Red Hat GmbH                 | Email: Phil Knirsch <pknirsch at>
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Motd:  You're only jealous cos the little penguins are talking to me.

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