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authorMike Gabriel <mike.gabriel@das-netzwerkteam.de>2018-03-17 22:59:24 +0100
committerMike Gabriel <mike.gabriel@das-netzwerkteam.de>2018-03-17 22:59:24 +0100
commit36c1d28e6fc34a39360f063cf2a375fe4df1363a (patch)
treecdbdf6ae3131dccf525567d3129593c9a26f9076
parent539526a966c70defca6f355676d220f8b2968fd5 (diff)
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Formulate README.md properly.
-rw-r--r--README.md69
1 files changed, 58 insertions, 11 deletions
diff --git a/README.md b/README.md
index 9e0b19c..1c931d4 100644
--- a/README.md
+++ b/README.md
@@ -1,17 +1,47 @@
-# Desktop Session (Pre-)Autoloader
+# Desktop (Pre-)Autoloader
-FIXME: this README.md needs to be beautified...
+This little project got inspired and co-authored by Klaus Ade Johnstad
+from https://linuxavdelingen.no.
-Old dirty hack. Stick this line in a file under /etc/rc.local.d/
-[ $(date +%s) -lt $(date -d 07:55 +%s) ] && su autoload -c "Xvfb :10 &
-DISPLAY=:10 /usr/bin/dbus-launch --exit-with-session startxfce4 &"
+The Desktop Autoloader project aims at being used on Diskless Workstations
+(aka LTSP Fat Clients).
+
+In class rooms or similar PC setups, a bottle neck occurs when all
+diskless clients startup simultaneously, students login simultaneously
+and start the same application(s) simultaneously. The storage devices of
+the serving machine cannot cope with all the simulataneous diskless
+clients demanding the same but slightly shifted file access on the
+server's NFS share or NBD block device (where the clients root filesystem
+is hosted).
+
+Observations have shown that diskless workstations work smoothly if
+people use them "asymmetrically", but become really really slow once 10 or
+more people use the diskless workstations in a symmetrical usage pattern.
+This normally happens when the users are students and follow instructions
+in class. We observed launch times for LibreOffice of 15min and more.
+
+The way to work around this bottleneck is taking advantage of the file
+system RAM cache of the Linux kernel. An application that has once been
+launched can be re-launched and during the re-launch it gets mostly
+accessed from the file system cache. This brings a tremendous
+acceleration to the usability experience of diskless workstations.
+
+## History
+
+This code project formalize and generalizes an old dirty hack:
+
+Stick this line in a file under /etc/rc.local.d/ [ $(date +%s) -lt $(date
+-d 07:55 +%s) ] && su autoload -c "Xvfb :10 & DISPLAY=:10
+/usr/bin/dbus-launch --exit-with-session startxfce4 &"
This will start things if the machine boots up before 07:55, combine
-this with wol, so things are up and running before pupils arrive.
+this with WoL, so things are up and running before people arrive.
Then, create a autostart.desktop file for the "autoload" user, which
logs him automatically out after 90 sec, like this:
-/home/autoload/.config/autostart/sleepandkill.desktop
+
+```
+$ cat /home/autoload/.config/autostart/sleepandkill.desktop
[Desktop Entry]
Encoding=UTF-8
Name=sleepandkill
@@ -19,16 +49,33 @@ Exec=/bin/sh -c "sleep 90; pkill -u autoload"
Terminal=false
Type=Application
StartupNotify=false
+```
-I stick these desktopfiles in under
-/home/autoload/.config/autostart/ as well:
+I stick these desktopfiles in under ``/home/autoload/.config/autostart/``
+as well:
+
+```
firefox.desktop
geogebra.desktop
libreoffice-writer.desktop
sleepandkill.desktop
Thunar.desktop
+```
+
+That way Libre Office, Firefox, Thunar and Geogebra are already cached on the client.
+
+Dirty hack, but you notice the differene quite well.
+
+## The Generic Approach
+
+This code project attempts at a general approach of the above hack.
+Whereas the above hack only works well for XFCE desktops, the Desktop
+Autoloader project generalizes the concept and makes it compatible
+with various desktop environments.
+
+The currently supported (i.e., tested) desktop environments are:
+ * MATE
+ * XFCE
-That wau LO, FF, Thunar and Geogebra is already cached on the client.
-Dirty hack, but you notice the differene quit well.