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 Post subject: Tremendous power drain with new kernels
PostPosted: 21/09/2009, 8:30 
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Joined: 07/04/2009, 3:51
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If you use "powertop", you will see that this one process is responsible for constant wakeups:
hrtimer_start_range_ns
(and other processes associated with "tick_sched_timer" and "hrtimer_wakeup"

There is a bug report here:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/373245


It is being reported by many netbook users (google), and is a huge unsolved problem.


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 Post subject: Re: Tremendous power drain with new kernels
PostPosted: 21/09/2009, 14:19 
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Joined: 23/04/2009, 18:22
Posts: 95
Location: Padova, Italy
ossas81 wrote:
If you use "powertop", you will see that this one process is responsible for constant wakeups:
hrtimer_start_range_ns
(and other processes associated with "tick_sched_timer" and "hrtimer_wakeup"

There is a bug report here:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/373245


It is being reported by many netbook users (google), and is a huge unsolved problem.

thanks for the info, maybe it's a lot better to stick with jaunty...


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 Post subject: Re: Tremendous power drain with new kernels
PostPosted: 21/09/2009, 16:53 
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Joined: 07/04/2009, 3:51
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The problem is also in Jaunty. Install "powertop" though synaptics, then run "sudo powertop" to see for yourself.

You'll see that this process causes 70% of wake-ups. This may explain why Ubuntu's battery life is bad compared to windows, despite massive tweaking.

also, powertop suggests to do something about the camera (even though It's blacklisted on startup), and the USB. I've only tinkered with it for an hour.


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 Post subject: Re: Tremendous power drain with new kernels
PostPosted: 23/10/2009, 18:11 
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Joined: 07/04/2009, 3:51
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Someone in the bug report said that disabling Hyperthreading in bios reduces the number of wakeups per sec, and I confirmed this works.

While there seems to be only slight change in hrtimer_start_range_ns wakeups, my total wakeups were cut in half

before: 20 wakeups per sec, interval: 10 sec
after disabling HT: 11 wakeups per sec, interval: 20 sec

(this is with webcam, bluetooth, and wireless disabled, and left at idle).


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 Post subject: Re: Tremendous power drain with new kernels
PostPosted: 24/10/2009, 12:17 
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Joined: 08/09/2009, 19:34
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Has someone tried how much this increases battery life and reduces performance?


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 Post subject: Re: Tremendous power drain with new kernels
PostPosted: 24/10/2009, 16:56 
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Joined: 24/10/2009, 16:52
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I think it depends on the usage: if you let it idle on a regular basis, the battery lost will be higher than if you're typing a text or doing things without any interruption.

But that being said, i'm not completely sure, maybe someone with more knowledge will answer it in a more accurate way

JL


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