1GB and HIGHMEM with 2.4.20

[Oliver Tennert <tennert@science-computing.de>]

Hello all,

sorry for bothering you again, but maybe I need an explanation: can it be
possible that having exactly 1 GB of RAM constitutes a critical threshold
on a Linux system (2.4.20 kernel in this case)?

The environment is: Vanilla Linux 2.4.20 ( 4GB option), 1 GB RAM,
Athlon XP, 2 GB Swap partition, XFree 4.3.0 + NVIDIA driver (several different versions)

the phenomena I observe are:

1.) certain applications (KDE, mozilla) make the system
swap in and out excessively, until a total standstill is reached, then
slowly the system recovers (until the next thrashing).

2.) I get a load of "ldt allocation failed" messages

3.) it is impossible to attach/detach swap partitions while the system is
running certain applications, although the "free"-Output tells me _no_
swap space is used, nevertheless I get a "operation impossible" (or
similar) error message when entering " swapon/swapoff" command

At first, I considered it to be a KDE problem, because the problems
started when I upgraded to  KDE 3.1, but then I tried the
following (also nobody else using KDE 3.1 seems to experience the same
problems)

--> booting without swapspace activated totally eliminates the big
problem 1.). Problem 2.) remains, but affects only  programs unimportant
to me (like framebuffer splash screen and the like). Problem 3.) also
remains, but adding swap would reverse my workaround anyway.

Also:

--> the problems __never__ occured with __exactly the same__ installation
on another machine (Pentium III) with 384 MB RAM, 2 GB swapspace, same
graphics card etc.

I also learned that in similar cases, either removing some RAM or trying
out "mem=<less than 1 GB>" option in the kernel command line helps.
But that seems a bit unelegant to me.

Is this behaviour normal?

Can you give me some help, or at least a hint what I can try?

Best regards for your help.

Oliver Tennert



		   Dr. Oliver Tennert

  		   +49 -7071 -9457-598

 		   e-mail: O.Tennert@science-computing.de
  		   science + computing AG
  		   Hagellocher Weg 71
   		   D-72070 Tuebingen


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