X-Git-Url: http://pere.pagekite.me/gitweb/homepage.git/blobdiff_plain/f349c402aec15a0f6c4f16c75e397f72003cfe87..f16471a8c97f25cdb4df50f4f744182684b291b1:/blog/index.html diff --git a/blog/index.html b/blog/index.html index 1b55c02965..f8cfac0120 100644 --- a/blog/index.html +++ b/blog/index.html @@ -19,6 +19,66 @@ +
+
Why the KDE menu is slow when /usr/ is NFS mounted - and a workaround
+
6th April 2012
+

Recently I have spent time with +Skolelinux Drift AS on speeding +up a Debian Edu / Skolelinux +Lenny installation using LTSP diskless workstations, and in the +process I discovered something very surprising. The reason the KDE +menu was responding slow when using it for the first time, was mostly +due to the way KDE find application icons. I discovered that showing +the Multimedia menu would cause more than 20 000 IP packages to be +passed between the LTSP client and the NFS server. Most of these were + +NFS LOOKUP calls, resulting in a NFS3ERR_NOENT response. Because the +ping times between the client and the server were in the range 2-20 +ms, the menus would be very slow. Looking at the strace of kicker in +Lenny (or plasma-desktop i Squeeze - same problem there), I see that +the source of these NFS calls are access(2) system calls for +non-existing files. KDE can do hundreds of access(2) calls to find +one icon file. In my example, just finding the mplayer icon required +around 230 access(2) calls.

+ +

The KDE code seem to search for icons using a list of icon +directories, and the list of possible directories is large. In +(almost) each directory, it look for files ending in .png, .svgz, .svg +and .xpm. The result is a very slow KDE menu when /usr/ is NFS +mounted. Showing a single sub menu may result in thousands of NFS +requests. I am not the first one to discover this. I found a +KDE bug report +from 2009 about this problem, and it is still unsolved.

+ +

My solution to speed up the KDE menu was to create a package +kde-icon-cache that upon installation will look at all .desktop files +used to generate the KDE menu, find their icons, search the icon paths +for the file that KDE will end up finding at run time, and copying the +icon file to /var/lib/kde-icon-cache/. Finally, I add symlinks to +these icon files in one of the first directories where KDE will look +for them. This cut down the number of file accesses required to find +one icon from several hundred to less than 5, and make the KDE menu +almost instantaneous. I'm not quite sure where to make the package +publicly available, so for now it is only available on request.

+ +

The bug report mention that this do not only affect the KDE menu +and icon handling, but also the login process. Not quite sure how to +speed up that part without replacing NFS with for example NBD, and +that is not really an option at the moment.

+ +

If you got feedback on this issue, please let us know on debian-edu +(at) lists.debian.org.

+
+
+ + + Tags: debian edu, english. + + +
+
+
+
Debian Edu in the Linux Weekly News
5th April 2012
@@ -624,60 +684,6 @@ Edu users in this country has to be part of it.

-
-
Writing and translating documentation in Debian Edu
-
16th March 2012
-

Documentation in Debian Edu is provided in several languages, and -it is important to make it both easy to contribute and to keep the -translated versions in sync. To do this we have come up with what we -believe is a very efficient work flow.

- -
    - -
  1. The documentation is written in a -moinmoin wiki (see for example -the -Squeeze release manual) with support for exporting the content as -docbook XML.
    2. - -
  2. This docbook document is given to po4a to extract a gettext style -.pot file with the content, which in turn is used to create .po files -with the translated text.
    3. - -
  3. The .po files are given to translators, and they can always tell -which part of the original wiki document is new or changed. They can -use their normal translation tools like lokalize or poedit to write -the translation. There is even a system in place to handle translated -images.
    4. - -
  4. The translated .po files are combined with the original docbook -XML document using po4a to create a translated docbook document.
    5. - -
  5. The final step is to use all the generated docbook files and -create PDF and HTML version of the original and translated documents.
    6. - -
- -

This setup work very well, but have a few issues. The biggest -issue is that the docbook support -we use in moinmoin is not actively maintained. The docbook -support is also buggy, and our build system contain workarounds to -make sure the generated docbook is usable despite these bugs.

- -

If you want to have a look at our setup, it is all there in the -debian-edu-doc -package.

-
-
- - - Tags: debian edu, english. - - -
-
-
-

RSS feed