Thin Clients freezing in Firefox

[Jim Kronebusch]

The client has 128MB RAM which must be shared with video.  It looks like by default the
client is allocating 32MB to video (as seen when running free at a shell on the client).
 It is only leaving 2MB free out of 128MB.  I assume this explains the crashes.  I tried
running xrestop but it appears to freeze almost immediately when I hit the page in
question, the last update says firefox is using just over 2MB.  Is there any way I can
put in a setting to force the client to not use so much?  I can't find any place to
change the settings in the bios.

I just added X_COLOR_DEPTH = 16 to lts.conf, we'll see if that helps.

Thanks for your help.  Things are not looking good for the school year if I can't get
this solved.

> That's not something that can be controlled via software.
> 
> IF it's possible to change the amount of video memory, it would be in 
> the bios of the thin client.
> 
> But, I'd be pretty surprised if you are running out of video ram.  If 
> anything, you've probably got too much video ram allocated.  If you 
> could reduce it to something reasonable, like 4mb, that would leave more 
> for the system.
> 
> When calculating the amount of video ram needed, as long as you aren't 
> running any GL stuff.  The general formula is:
> 
>      horizontal resolution * vertical resolution * color-depth-in-bytes 
> = ram-needed.
> 
> If you are running 16-bit color (2-bytes) and 1024x768 resolution, then 
> it's:
> 
>     1024 * 768 * 2 = 1,572,864  (a bit more than 1.5mb).
> 
> with 4mb of video ram, you could easily do 1600x1200 with 16-bit color.
> 
> I'm not sure what the default color depth is for Ubuntu/LTSP.  If it's 
> 24-bits, try reducing it to 16-bits.  That might help.
> 
> Almost always, if you are browsing the web and the terminal locks up, 
> it's because the firefox has asked the Xserver to allocate some memory 
> to hold bitmaps or fonts, but the thin client doesn't have enough free 
> memory to accommodate the request.  The Xserver then locks up and that's 
> the end.
> 
> If the T150 lasts longer before locking up than the Devon, then it 
> probably indicates that the T150 has more usable memory than the Devon.
> 
> Enabling swap *should* help.
> 
> Adding more physical ram should help even more.
> 
> Also, there's a cool program called 'xrestop'.  You can apt-get install 
> that and run it.  It's an X app, so you can run it on the server and 
> it'll monitor your Xserver on your client.
> 
> It is sort of like the 'top' utility, but rather than showing process 
> status, it shows resource status within the Xserver.  Of particular 
> interest is the column called 'Pxm mem'.  that's the amount of memory 
> the Xserver has allocated for pixmaps per X client app.  The total 
> pixmap memory is also displayed in the top section.
> 
> Try running that AND firefox at the same time, if you can see them both 
> on the screen simultaneously, after you've been browsing for a bit and 
> the terminal locks up, you should be able to see the last snapshot of 
> the resources.  Might tell you exactly what's going on.
> 
> Jim McQuillan
> jam at Ltsp.org
> 
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Jim Kronebusch
Cotter Tech Department
453-5188


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