# 2.6.37: system becomes unresponsive sometimes (kworker?)

## Fran

Since I updated to 2.6.37 sometimes my laptop becomes unresponsive for several seconds. It seems to happen randomly. This is VERY annoying. I upgraded to 2.6.37 because my old trusty 2.6.34.7 kernel was sluggish with the latest X (maybe the driver's fault?). 

Anyway, the problem seems related to the fucking kworkers hogging the cpu randomly. I must say I had A LOT of problems with kernels >=2.6.35 due to the fucking kslowd/kworker processes hogging the cpu at random intervals (or even constantly). That's why I was still using 2.6.34.7, it's the last kernel without these problems.

Is there anyone else with this problem? Any solution? Anything I can do to understand WHY kslowd/kworker processes have been fucking me over for months in my laptop? (my desktop computers work flawlessly).

Thanks.

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## frostschutz

I'm stuck with 2.6.34 on one machine as well. 2.6.35 and above cause KVM instances to hang at 100% CPU usage, sometimes indefinitely. For me it's related to my network card, though. It's a Realtek, and sometimes when there's a bit of traffic it gets a hiccup and the problems in the VM start at the same time. It didn't happen so far in 2.6.34.x. So I believe there is some kind of regression in >= 2.6.35. There are changes to this particular network driver in almost every kernel version so I keep hoping the problem will go away but so far no luck.  :Laughing: 

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## Hu

For both of you, could you provide links to your respective upstream bug reports?  Any future users who are affected by the same problem and find this thread would probably appreciate being able to quickly check for resolution in the upstream report.

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## Fran

 *Hu wrote:*   

> For both of you, could you provide links to your respective upstream bug reports?  Any future users who are affected by the same problem and find this thread would probably appreciate being able to quickly check for resolution in the upstream report.

 

Hmm... that's not how I work. Before I post a bug in bugs.*.org I always make sure it IS a bug and not my hardware or simply PEBKAC. That's why I ask in forums if there is someone else with the problem (if it is a bug, surely someone else must have experienced it, I have a common Acer 1810TZ laptop). For example, my problems with a jerky trackpad when using the .35-.37 kernels (not with .34, however) disappeared when I switched from synaptics to pure evdev (I lose some nice features, but smoothness is way more important for me). I was sure it was some kernel bug, but it seems to be a weird combination of kernel version/synaptics/hardware.

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## frostschutz

I'd do a git bisect, if it wasn't on a server that's supposed to be running... and I don't report bugs when I don't have any useful info to provide (there are tons of "it doesn't work" bug reports regarding this particular NIC already). Seems that Fran's issue is different anyhow, unless there's the same NIC in his laptop.

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## Adwin

I have the exact same issue, although I have noticed that this usually happens when I'm in X (I haven't noticed this happening in console-only mode).

I didn't run any troubleshooting though, which is why I cannot provide any more info.

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## forrestfunk81

Same problems here. ~amd64, sys-kernel/gentoo-sources-2.6.37, KDE-4.5.5

Sometimes Kworker uses nearly 100% of my dual core cpu. This happens within a KDE session, mostly after an idle period - go to the fridge, get a beer, come back, hit the mouse, wait 10 seconds for kworker  :Wink: 

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## Fran

Setting drm_kms_helper.poll=N at boot in grub.conf helped me get rid of the occasional slowdowns, but I get complete lockups instead (i.e., sometimes I must pull out the plug to reset the computer).

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## fragraider

Hi,

i think i am having the same problems. Sometimes my box seems to be quite unresponsive, top shows me two processes, kworker/u:1 and kworker/u:2 . Both seem to alternately cause a cpu-load between 10 to 40 percent.

Are there any news about this?

If I may ask, what is kworker for? I did not find anything useful online.

```
$ uname -msrv

Linux 2.6.36-gentoo-r5 #1 SMP Wed Dec 29 14:57:29 CET 2010 x86_64
```

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## patrix_neo

I think the kworker has to do with the CPU/Cores...just a shot in the dark...I guess, if so, it has to do with what core/cpu is doing the workload.

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## henri

Hi folks,

I've also had the problem since a few month that suddenly the system freezes for a few minutes and then I was able to work again, but also only for a few minutes.

I researched a lot and finally used htop to have a look which process could have taken all memory or cpu ressources and wondered that one processor loadbar was at 100% but no process was to see in the table that used the 100% cpu.

Strange... strange? Not really!

I simply forgot that in the setup of htop the display of kernel threads was diabled, so I turned it on again and voila:

The next freeze I could realize it was a kworker process which used all the cpu ressources.

But why did it need so much cpu ressources for such a long time?

Some further investigations lead me to the real-time-clock, which I have enabled in my kernel (like probably most of you have).

RTL ? Wait a second... some month ago, I had to upgrade the bios of my amilo Laptop, and remembered that I then set up the default values of the bios and only changed the use of the hybrid grafic-cards option to only use the nvidia card.

Ähhhhm... did I also reactivate the RTL in the bios?

I rebooted and took a look and: Oh, no! I forgot to turn the RTL on again. - Did it then and...

Hurray! - No more freezing kworker prozesses!

8<------------------------8<------------------------8<------------------------8<------------------------8<------------------------

If your system freezes for a few minutes, use for example htop, turn on the display of kernel threads (F2) to take a look if the reason may be a kworker process and if it is, take a look at your kernel RTL settings and asure yourself that the real-time-clock is enabled in your BIOS.

Yours Henri Schomäcker

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