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#1 2011-06-14 23:55:01

gauthma
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Registered: 2010-02-16
Posts: 188
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[Solved] System slows down when charging

My laptop battery got to a really low level (<5%), but it was working smoothly, until I plugged in the charger: after that, the system got sluggish (usable, but VERY annoying). I suspect this is related to the graphics card/driver (Intel/i915). By watching the output of top, there was a kworker process using consistently over 40% CPU (despite starting with a K, from what I could glean, this has nothing to do with KDE). Once the battery got over 90% (approx.), the system got usable again. Is this some misconfiguration issue? Bug? PEBKAC?

Last edited by gauthma (2012-01-24 15:25:16)

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#2 2011-06-15 03:50:10

Inxsible
Forum Fellow
From: Chicago
Registered: 2008-06-09
Posts: 9,085

Re: [Solved] System slows down when charging

That does seem weird. In fact its the first time I heard something like that. Was there some CPU intensive operations that you were performing along with the charging?

An interesting test would be to see if it happens again and consistently so. Try to discharge your battery to 10% and then put it back on charge to see what is going on. Maybe post your dmesg at that time and your Xorg.log (although at this point I am not quite sure what we will find)


A basic google search for kworker yields this :

http://www.google.com/search?sourceid=c … is+kworker

kworker seems to be some kind of indexing service. Disabling nepomuk might be one option as described here


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There's no such thing as a stupid question, but there sure are a lot of inquisitive idiots !

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#3 2011-06-15 09:36:18

einhard
Member
From: Poland
Registered: 2010-01-05
Posts: 89

Re: [Solved] System slows down when charging

Kworker handles the ACPI wakeup signals from the BIOS. It is not related to KDE. Does this issue occurs on pure console without DM (KDE)?

You may be right that the cause is Intel graphics driver, try installing latest git version from aur http://aur.archlinux.org/packages.php?ID=18678. I don't have Intel graphics card but is there possibility to turn off acpi on it?

What power managment solutions are you using? Try disabling temporary everything (pm-utils, acpid, laptop-mode-tools, powerdevil, etc.).

It may also be a kernel bug. I remember similar situation with 2.6.34.

As last resort you can turn off ACPI at boot (acpi=off on kernel line in grub.cfg or as option in grub console) but I don't think you really want that.

Last edited by einhard (2011-06-15 10:13:26)

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#4 2011-06-15 21:36:49

gauthma
Member
Registered: 2010-02-16
Posts: 188
Website

Re: [Solved] System slows down when charging

OK, it is happening again: charging and going into slug mode. It only happens with X, on the tty it runs smoothly. I haven't installed the driver from AUR, will do that next. I haven't disabled nepomuk, but it was a clean install, so I don't think it'll have much to index... (but I'll disable it nonetheless). As for power management solutions, it's still pretty much on the defaults. I haven't even implemented the suggestions for laptops on the wiki yet... Any setting on particular you're curious about?

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#5 2011-06-16 00:02:22

gauthma
Member
Registered: 2010-02-16
Posts: 188
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Re: [Solved] System slows down when charging

Also, the system became responsive again when the battery charge level hit +90%

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#6 2011-06-19 14:13:08

gauthma
Member
Registered: 2010-02-16
Posts: 188
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Re: [Solved] System slows down when charging

OK, this just got weirder. If the charger is plugged in *before* the battery level gets below 5%, then the system continues to work as usual. But if the charger is plugged after this level is reached, then the computer goes into unresponsive mode, but *only within X*. When in command mode (with AC power), the load average is about 0.20, but switching to X, and briefly moving the mouse, is enough to make the load average soar into >1.00.

I've done this a couple of times, to see if I could reproduce the behaviour, which is indeed the case.

(this is still without the driver version from AUR)

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#7 2011-07-26 09:34:36

theseus
Member
Registered: 2011-07-20
Posts: 19

Re: [Solved] System slows down when charging

I just want to say that I have the exact same problem.

My laptop is a Dell E5420 with an Intel graphical card.

And it is for sure related to the moment you plug the battery. I tried this sequence:

- low battery (lower than 10% for sure but can't remember exactly how low)
- plug the battery
  ==> kworker wakes up and slows down my machine
- wait a few minutes
- unplug the battery charger (battery not full!)
  ==> kworker behaves normally and my laptop is fully usable again at a normal load)
- re-plug the charger
  ==> bahm! kworker is back
- and also around 90%, it behaves correctly.

I checked on the BIOS side but couldn't really see anything relevant.
I also tried the "pcie_ports=compat" option on the kernel command line but no luck.

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#8 2011-08-23 07:41:49

theseus
Member
Registered: 2011-07-20
Posts: 19

Re: [Solved] System slows down when charging

I don't remember where I got this from, but I added the following option on my kernel at boot and so far so good! (I didn't extensively tested, only twice, but I didn't see the ugly kworker popping up anymore).
Here is the magic trick:

drm_kms_helper.poll=N

If someone else has the same kind of problems, please see if this helps.

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#9 2012-01-24 15:24:54

gauthma
Member
Registered: 2010-02-16
Posts: 188
Website

Re: [Solved] System slows down when charging

theseus wrote:

I don't remember where I got this from, but I added the following option on my kernel at boot and so far so good! (I didn't extensively tested, only twice, but I didn't see the ugly kworker popping up anymore).
Here is the magic trick:

drm_kms_helper.poll=N

If someone else has the same kind of problems, please see if this helps.

I can't believe this answer is here since August! Saw it yesterday, and yes this solved my problem! Thanks very very much! big_smile

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