# Laggy GUI applications with kernel 3.2.0

## Voltago

So after using linux-2.6.39 for ages, I recently upgraded to linux-3.2.0-gentoo-r1 and ran into a problem that is rather hard to diagnose: After an uptime of two, three hours, the GUI of some (not all!) applications starts to get unresponsive and laggy. First, firefox and thunderbird are affected, and KDE's plasma desktop a little later. The applications just freeze up for 10-20s, then behave normally for a short time, then freeze up again. There doesn't seem to be any uncommonly high CPU usage going on at the time, and no unusual memory usage.

Has anybody witnessed similar behaviour in recent kernels?

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## avx

For me, Opera sometimes has these short-time freezes, too. Don't know if it's related to the kernel or an Opera-bug, though.

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## Voltago

Actually in my case it's rather short-time-unfreeze. I'm positive that what I'm seeing is somehow kernel-related (it might be a userland bug somewhere that shows up with the new kernel). Does reverting to an older kernel make your freezes go away?

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## avx

Hard to tell, I've got no way to forcefully reproduce this, yet. Besides, here Opera is the only GUI-application on this box, everything else runs fine, sorry.

Now that I've finally got WLAN on this machine - only took a year, damn Broadcom - I'd rather not downgrade and lay out all the cables again  :Twisted Evil: 

BTW, this is my notebook I'm complaining about, my desktop doesn't have this problem(as of now).

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## toralf

Hhm, I observed a similar behaviour with newer kernel - and dunno how to reproduce it. But sometimes it is related to my wlan which suddenly stops working w/o any messages ...

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## Voltago

For the record, my troubles were apparently caused by one of the kernel boot parameters

```
i915.i915_enable_fbc=1 i915.lvds_downclock=1
```

which are supposed to lower power consumption for Intel integrated graphics.

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## toralf

 *Voltago wrote:*   

> For the record, my troubles were apparently caused by one of the kernel boot parameters
> 
> ```
> i915.i915_enable_fbc=1 i915.lvds_downclock=1
> ```
> ...

 For me there were only few power consumptions tips useful.

 One is to use the patch of kernel 3.2.5 (or 3.0.20) - that saves ~3 W. Beside that these helped me :

```
 $ sudo cat /etc/local.d/power.start 

#!/bin/sh

#

#

#       power saving

#

F=/sys/devices/system/cpu/cpufreq/ondemand/ignore_nice_load

if [[ ! -f $F ]]; then

        echo "module acpi_cpufreq not loaded ?!"

        modprobe acpi_cpufreq

fi

echo 1 > $F || echo "$F doesn't exist !"

/usr/sbin/ethtool -s eth0 wol d

/usr/sbin/hciconfig hci0 down

/sbin/iwconfig wlan0 power on

echo 3000 > /proc/sys/vm/dirty_writeback_centisecs

```

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## Voltago

Thanks, Toralf. By the way, I noticed that by default my system has

```
linux ~ # cat /proc/sys/vm/dirty_writeback_centisecs 

60000

```

600 seconds for dirty_writeback seems a bit high. Should I be alarmed?

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## nikulinpi

Same problem! I bet it should be related to some kind of cgroups nastiness

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## toralf

 *Voltago wrote:*   

> Thanks, Toralf. By the way, I noticed that by default my system has
> 
> ```
> linux ~ # cat /proc/sys/vm/dirty_writeback_centisecs 
> 
> ...

 Did you installed app-laptop/laptop-mode-tools ?

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## nikulinpi

http://www.linuxquestions.org/questions/linux-kernel-70/extremely-sluggish-system-with-newest-kernels-under-high-memory-load-933664/

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## nikulinpi

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=594923

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