poor multimedia performance on LTSP clients

[Matt Keys]

See http://ubuntuforums.org/showthread.php?t=1013767 . Video, either streaming or locally stored, on LTSP clients is horribly slow regardless of what the server or client hardware is.

[Robert Dyer (psybers)]

I tested LTSP a bit on an empty 100mbps lan, with a video playing choppy (tried youtube videos in Firefox and some *small* 320x mpeg). Watched the bandwidth usage on the router and it was < 1mbps so network isn't an issue.

The server and the test client were both very high power/memory (not a 'thin' client at all). Memory usage and CPU usage on both were fine (verified LTSP usage w/ local root login).

The client had the Nvidia drivers enabled, though also using the open-source driver gave similar result.

It appears the problem is completely unrelated to hardware, as mentioned. Perhaps the latency on the network (I don't know this networks latency, though the client and server are in the same room with only 1 switch between them) is large enough to cause a problem, but at 30fps I wouldn't think that is the case.

[Matt Keys (mk6032)]

Out of curiosity what is your fps rate from glxgears? Smooth or horribly choppy?

[Robert Dyer (psybers)]

It looks choppy, though it delightfully claims to have 3800 FPS (850 FPS @ 1024x768 full screen). Re-verified bandwidth usage on a HQ youtube video (normal and full-screen) was at the most 732kbps/92kB/s, server cpu load was 30% on 1 core with several GB free memory.

Another thing I have noticed is the zoom animations in GNOME Do's Docky are horribly choppy/slow too. But then animations in Compiz (wobbly windows, dragging it around fast) seem to display/update just fine!

I might also point out that I set LDM_DIRECTX=True to disable SSH tunnels, which should reduce loads.

[Matt Keys (mk6032)]

Are there any updates on this? Have the LTSP devs been notified?

[Christian (c-pradelli)]

Some application that I run using wine (IBExpert for example) are unusable due to this bug. I need to run wine as local application to use it.

[Stéphane Graber (stgraber)]

LTSP doesn't have its own network protocol or anything like that, it's simply doing X11 over the network.
For multimedia heavy applications, the upstream opinion on the matter is to use Local applications, that's the reason why we implemented this.

Usually setting LDM_DIRECTX=True (not by default for security reason), using hardware with 3D working drivers over the network (like Intel) and running multimedia intensives applications locally works perfectly.

Intel graphic is so far the only video cards that i saw working correctly with 3D over the network (AIGLX and GL), at least ATI don't work correctly (with free or binary drivers), not sure for Nvidia.

In all cases, it's not an LTSP bug and there is nothing upstream can do to help you with that other than working on improving local applications support (which is already quite good now).