Dear Helmut & everybody,
I found solution (better say workaround) for graphics performance
problems under new LTSP, which were reported few months ago by me, and
by Helmut few weeks later. It i now clear that it is not problem in LTSP
itself, neither X window manager, but somenthing is broken probably
inside X. I was doing these tests with Radeon driver and also SIS
driver, and i've got same results so this is probably nor related to
graphics chipset/driver.
I have found that performance problem depends on X server which running
inside thin client, and it does not depend on version of LTSP/XDMCP
server. If I use any of current distributions (*ubuntu 14, debian 7,
opensuse 13, ...) on thin client, then graphics performance is very
poor. If I use much older distribution on X client (while connecting to
the same LTSP/XDMCP server with current distribution), performance is
much better. Again - to get very good performance, I can run new
distribution on terminal server, but I have to run very old distribution
on thin clients.
To compare results, I did two tests with apps, where we could clearly
see the difference:
(1) oocalc test - start oocalc, select maximum possible cells on the
screen, press ctrl-c to draw selection background and dashed line around
it, and then press cursor down key 10-times, as fast as possible, and
count how long does it take to redraw selected area (deselect it) and
move cursor from 1st cell to 10th, while dashed line is still
continously (re)drawn. Test has been repeated and final values are averages:
openSUSE 11.0 (xorg-server 1.4.0, radeon 4.2.0) => *1.7* second
openSUSE 11.1 (xorg-server 1.5.2, radeon 4.3.0) => *2.3* second
openSUSE 11.2 (xorg-server 1.6.5, radeon 6.12.4) => *1.7* second
openSUSE 11.3 (xorg-server 1.8.0, radeon 6.13.0) => *2.6* seconds !!
openSUSE 11.4 (xorg-server 1.9.3, radeon 6.14.0) => *3.3* seconds !!!
openSUSE 12.1 (xorg-server crash, radeon unknown) => unknown
openSUSE 12.2 (xorg-server 1.12.3, radeon 6.14.4) => *5.5* seconds !!!!!
openSUSE 12.3 (xorg-server 1.13.2, radeon 7.0.0) => *11.3* seconds
!!!!!!!!!!!
(2) rdesktop test - connect to WinXP machine running TSreader
application, which is redrawing its window contents every 1 second, and
look how long does it take to redraw the window on thin client.
openSUSE 11.0 (xorg-server 1.4.0, radeon 4.2.0) => *superfast *(few
mililseconds)
openSUSE 11.1 (xorg-server 1.5.2, radeon 4.3.0) => *superfast *(few
mililseconds)
openSUSE 11.2 (xorg-server 1.6.5, radeon 6.12.4) => *fast* (little
flicking is visible)
openSUSE 11.3 (xorg-server 1.8.0, radeon 6.13.0) => *fast* (some
flicking is visible)
openSUSE 11.4 (xorg-server 1.9.3, radeon 6.14.0) => *slow* (flicking is
very visible)
openSUSE 12.1 (xorg-server crash, radeon unknown) => unknown
openSUSE 12.2 (xorg-server 1.12.3, radeon 6.14.4) => *slow* (flicking is
very visible)
openSUSE 12.3 (xorg-server 1.13.2, radeon 7.0.0) => *extemely slow*
(client is not able to draw whole window in 1 second intervals)
I did similar tests with some older *ubintu, Debian and CentOS
distributions, and similar xorg-server version gave me similar results.
Unfortunately I don't know how to fix it with current distributions, but
I'm happy that If I run ~7 years old openSUSE 11.2 on thin client,
performance problems are gone.... :o)
Regards,
Michal
Dňa 02/18/2015 o 10:16 AM Helmut Lichtenberg napísal(a):
Hi Alkis,
Alkis Georgopoulos schrieb am 17.02.2015 16:38:
Maybe you're using a compositing window manager?
Everything is still ok here with Ubuntu 14.04 and the gnome-flashback
session (metacity window manager without effects).
it's good to hear that Gnome (e.g.) is running fast. So it's possible.
But we made a decision to use KDE in 2000! At this time, KDE was the most
complete window manager and this was an important reason to migrate common
users to a Linux desktop. Since then we have a userbase of 40-60 colleagues
(scientists, technicians, administration) using a KDE-Linuxdesktop on thin
clients. Around the middle of the 90s we switched to LTSP.
It is no option to switch from KDE to Gnome, xfce or any other window manager
only because a problem occurs. We have to solve it. Most of our users only
want to manage their daily work efficiently. They don't have lots of computer
skills. Rolling out a new window manager means a lot of work and likely yields
new/other problems.
If you think that graphics in general are slower, and it's not a
window-manager/compositing issue, then try x11perf, gtkperf or something
similar to compare the results with the older installation.
How can I know if it is an "window-manager/compositing issue"?
The KDE window manager kwin uses either OpenGL or XRender. I found no
significant differences between those.
In my opinion this must be handled automatically. When I sometimes work with
my same account on AMD-, Intel-, or VIA-based clients I (the users) don't want
to always change some rather internal options like the composite type.
I only can imagine some generic options either on the server or on the client
side about things like compression, encryption, or general thin client
options.
I really would appreciate some hints, how to systematically get closer to the
problem.
Thanks
Helmut
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