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Old 25th January 2012, 11:15 PM
old486whizz Offline
Registered User
Join Date: Jan 2008
Posts: 34
Strange output pausing....

Hiya guys, I was wondering if anyone could help me or point me in the right direction.

I have been noticing for a long time that whilst using konsole the output to the screen pauses for a long time if I do not give the CPU an interrupt (ie, move the mouse or tap a key).

This is very visible if I do an "ls -l" and some symbolic links are broken (the flashing is very bad).
It occurs whenever I type in a command. Sometimes a simple ls will look like it has hung, but 2 minutes later a mouse move or keypress will reveal the output.

I don't notice it while using other applications (I don't know if animations look smoother while moving the mouse or not), but it does puzzle me.
I've tried looking at the logs in /var/log and can't see anything specific, and searching google produces various rubbish about crashing - I must be missing a keyword.

I don't notice it in virtual terminal 2, so it must be X or KDE causing this problem, and it's not just konsole (I've used xterm and the odd pausing still happens).

Any ideas are greatly appreciated.

(Currently I'm running Fedora 15, with KDE 4.6.5 - although I seem to remember it also happened in Fedora 13, and 14 - so I think it's a rogue setting and not just a version problem)
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Old 26th January 2012, 12:44 AM
Posts: n/a
Re: Strange output pausing....

That is pretty odd. Not so long ago the kernel would reschedule processes on clock-ticks, but that's no longr the default.

Which fedora and which kernel are you using ?
What added kernel options are you using in grub/grub2 ? noapic or hpet or anything like that ?
What is your hardware/modo/cpu like ?

Is your system losing time when you examine the 'date' command output too ?

Does 'su -c powertop' show anything odd for "Top causes of wakeup" ? Should show a pageful of apps with varying percentages.

Last edited by stevea; 26th January 2012 at 12:48 AM.
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Old 26th January 2012, 01:01 PM
old486whizz Offline
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Join Date: Jan 2008
Posts: 34
Re: Strange output pausing....

Thanks for replying.

I'm using an AMD Athlon X3 cpu with ati card (ati binary blobs for graphics).

Fedora: 15
The grub line has no customizations:
ro root=/dev/mapper/rootvg.sophie-rootlv rd_DM_UUID=nvidia_fbabgcfb rd_LVM_LV=rootvg.sophie/rootlv rd_LVM_LV=rootvg.sophie/swaplv rd_NO_LUKS rd_NO_MD LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYTABLE=uk rhgb quiet
The parts of the Xorg.conf file that might matter:
Section "ServerFlags"
        Option      "AIGLX" "on"
        Option      "XGL" "on"
        Option      "BlankTime" "0"
        Option      "StandbyTime" "0"
        Option      "SuspendTime" "0"
        Option      "OffTime" "0"

Section "Device"
        Identifier  "Videocard0"
        Driver      "fglrx"
        Option      "OpenGLOverlay" "off"
        Option      "OverlayOnCRTC2" "1"
        Option      "Capabilities" "0x00000800"
        Option      "BackingStore" "on"
        Option      "UseFastTLS" "2"
        BusID       "PCI:2:0:0"
.... hmmmm, I suppose I should try removing the ATI catalyst drivers, try again after that... I'll also try fiddling with a few more settings.
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Old 15th June 2012, 09:01 PM
meffordm Offline
Registered User
Join Date: Mar 2008
Posts: 13
Re: Strange output pausing....

Hey guys...anymore info on this? I seem to have the same issue on my netbook. I also notice it during audio playback (will loop until interrupted). My screen also pauses until interrupted and I am losing time. It looks like the system enters an idle loop when this is happening.

Fedora 17
Kernel: 3.4.0-1
System: Asus Eee PC 1201ha
Processor: Intel Atom z520

---------- Post added at 02:01 PM ---------- Previous post was at 10:48 AM ----------

Ok, I think I fixed it...at least nothing is looping or pausing...yet. Do this in Fedora 17:

As root, backup /etc/default/grub (I just copied it to /etc/default/grub.bkup). Then add nohz=off to the GRUB_CMDLINE_LINUX line in /etc/default/grub, like this:

GRUB_CMDLINE_LINUX=" <...a bunch of stuff here...> nohz=off"
Next, backup /boot/grub2/grub.cfg (Again I just copied this to /boot/grub2/grub.cfg.bkup). Now run:
[root@localhost ~]# grub2-mkconfig -o /boot/grub2/grub.cfg
This will add nohz=off to your kernel boot options. Reboot and enjoy.
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Old 15th June 2012, 09:10 PM
marko Offline
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Join Date: Jun 2004
Location: Laurel, MD USA
Posts: 7,097
Re: Strange output pausing....

That will have the effect of making the kernel run without being tickless. It's probably a pretty good compromise for solving your pause problem but if your machine is a laptop you'll use a bit more battery.

Last edited by marko; 15th June 2012 at 11:20 PM.
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Old 15th June 2012, 09:37 PM
meffordm Offline
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Join Date: Mar 2008
Posts: 13
Re: Strange output pausing....


I know, but for now I favor performance.
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