Ubuntu my first experience

Recently I wrote an Article about my first experience with Kubuntu, which is, as i understood, Ubuntu + KDE. This time, I’m taking a look at Ubuntu.

Alright. The Installer is as easy as at Kubuntu (Surprise, Surprise) differences are: The time is shown correctly this time (Oo). I’m at the partitioning screen and I’m setting the following partitions:

    /dev/sda1     ext4    /boot        98 MB p
    /dev/sda2     swap    swap       4095 MB p (should have been 4096)
    /dev/sda3     ext4    /         10240 MB p
    /dev/sda5     ext4    /home    499998 MB l
    Free Space:                    485769 MB 

I pretty like that Installation stuff, as I already wrote at the Kubuntu Article, the only thing I’m missing is a network settings dialog, at least optional. At a first look, there are also no translation mistakes in the install-screens.

The first boot

Was working without trouble. :) Well, it’s very fast up. They did a real good Job there. Network configuration was easy and worked fine. First update worked without trouble, too. I just installed some apps, configured email. Everything works fine so far, even the translations. I really have nothing bad to say, yet. Maybe the graphic glitches of the login/logout screen, which are caused by the driver (tho thats not ubuntu’s fault).


Well there’s a good guide here: wiki.ubuntuusers.de/tuning for the german users reading this. In simple:

  1. Switching from getty to fgetty
  2. Modifying /etc/fstab
    1. …to use /tmp as tmpfs
    2. …to have tmpfs in /dev/shm (for later use with qemu, iirc also skype uses that)
    3. …to set “noatime” everywhere except for /home where i set relatime
  3. Tuning the filesystem a bit using tune2fs
  4. Disabled graphical effects

The second day

Hehe. I can compare the ubuntu installation only with other distributions as I never used Ubuntu before; Also I never used Gnome, so I can compare that only to xfce4. Please keep that in mind, if i do comparisations :)

Problem #1

Compared to Lunar with xfce4, Ubuntu has probably some issue with XOrg or Gnome, regarding XOrg and Nautilus. If I take a look at my Lunar Linux (xfce4) installations I notice the following:

    Idle                          :     0% XOrg cpu usage
    Moving the mouse very fast    :     8% XOrg cpu usage

If I take a look at Ubuntu (effects disabled: so no compiz. Not using unity. glxinfo | grep render doesn’t show Software Rasterizer. ATI KMS) I notice the following:

    Idle                          :     0% XOrg cpu usage
                                        0% Nautilus cpu usage
    Moving the mouse very fast    : 15-25% XOrg cpu usage
                                    15-25% Nautilus cpu usage

So if you sum that up and if you imagine playing a game where you need to move the mouse a lot and very fast (i.e. some fast paced ego shooter) you’ll end up with 30-50% CPU usage just by using the mouse. (This is only half true because I haven’t checked (yet) whether this happens also if you’re ingame – However, 30-50% cpu usage caused by nautilus+xorg together just by moving the mouse real fast seems very weird to me)

Whats causing that, and what I can do against that, I really have no idea; I already asked on the #ubuntu irc freenode channel where a handful of people tried to help me (thanks!) but I’m just able to limit the load not to solve the root-issue. For example my above improvements caused the cpu usage to go down to ~11% for each xorg and nautilus (so ~20% CPU usage now, when moving the mouse real fast) if I ignore nautilus, we’d talk about 8 to 10% which I’d take as normal and thus I guess it’s a problem with nautilus.

If I change the mouse polling to 500hz (in games I’m used to use 500hz to 1000hz, especially with fast paced ego shooters – And on the other box where I have 8% xorg load I’m using 1000hz) I get the following result:

    Idle                          :     0% XOrg cpu usage
                                        0% Nautilus cpu usage
    Moving the mouse very fast    :    50% XOrg cpu usage
                                       17% Nautilus cpu usage

What the… 67% cpu usage just for moving the mouse? I’m using a razer abyssus, it’s an usb gaming mouse. On the backside of it, you can set 125hz and 1000hz. If I turn the switch from 1000hz to 125hz all is fine – Maximal cpu usage of XOrg is at 5%. I can still adjust the polling rate in linux manually (I know how, I’m not sure how to verify that the mouse is driven using that polling rate)

However, it’s quite weird because you’re searching for some “graphical” issue and it turns out it was a usb/mouse driver issue or the mouse itself.

Problem #2

This one was very difficult to spot. And I did a lot of things, to try to come around this. It was very good that I had this issue, because of that I did a lot more with Ubuntu than I planned to do. Alright. The problem: While loading Ubuntu, while shutting down Ubuntu, while the screensaver starts and when the visualization plugin of rythmbox starts, the Screen is flickering. The Graphiccard is an ati x1200 series (r300) on board. First I tried to disable compiz. Then I tried to upgrade from LTS to 10.10, then I tried to update from 10.10 to the latest. Then I tried a newer Kernel. At all Variants I tried with xorg.conf and without, with various settings (and as already wrote, with and without compiz) nothing of that was solving the issue. So I added the experimental repository of xorg/mesa etc to ubuntu’s source stuff and tried to use that (i.e. i tried to use Galium) – this reduced the flickering, it was still around, tho.

After reading hundreds of pages, because people having a lot trouble with such cards and opened a lot of bugreports I found the cause and a fix.

Basically some app is querying randr to get the monitors. This causes the flicker. You can reproduce that by issuing “xrandr”. If your screen flickers – You’ve got the same issue. You can stop that behavior by issuing:

xrandr --output  --set "load detection" 0

Where “” should be replaced by the correct output, obviously. In my case that’s “VGA-0″. And no, this didn’t solve the issue – Because there’s another output which got queried. S-Video. Issuing

xrandr --output S-Video --set "load detection" 0

finally solved the issue. No more flickering. You can check which outputs you have, and whether load detection is enabled by issuing:

xrandr --verbose | egrep ^[A-Z]\|load\|CRT

it’ll output something like:

Screen 0: minimum 320 x 200, current 1280 x 800, maximum 8192 x 8192
LVDS connected 1280x800+0+0 (0x55) normal (normal left inverted right x axis y axis) 331mm x 207mm
        CRTC:       0
        CRTCs:      0 1
DIN disconnected (normal left inverted right x axis y axis)
        CRTCs:      0 1
        load detection: 1 (0x00000001)  range:  (0,1)
VGA-0 disconnected (normal left inverted right x axis y axis)
        CRTCs:      0 1
        load detection: 1 (0x00000001)  range:  (0,1)
DVI-0 disconnected (normal left inverted right x axis y axis)
        CRTCs:      0 1
        load detection: 1 (0x00000001)  range:  (0,1)

This is on another box, tho you can see quite easily where “load detection” is enabled (1) and exactly that was causing the flicker. You can find more information about that by reading this link.

My Conclusion so far?

Well, everything works as it should. I got good and friendly help on the #ubuntu channel, I found a lot of useful information while googleing about ubuntu… So far, I think I could suggest this distribution to linux beginners with peace of conscience.

Well done.

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