Memory management

[Christoph Bier]

Hi all,

maybe the devel list would be the right place for this mail. But I'm
not sure and try it here first.

During the last months I tried to track down severe stability and
performance problems (described here [1]) on my laptop. It regularly
froze (and woke up after 5 to 90 minutes again) but I did not know
why. I upgraded to Dapper hoping that some improvements for laptop
support may have solved the problems. But the problems stayed the
same. Then a few weeks ago I accidentally found that system freezes
reproducible when 80% of memory usage is reached---under any
circumstance. And indeed after installing another 256 MB of memory
(now altogether 512 MB minus 32 MB shared video memory) Ubuntu runs
stable and with good performance on my laptop again. But this is
strange for the following reasons:

1) On a Breezy desktop machine with similar (even older) hardware
stability or performance problems do not appear at all.

Laptop hardware:
----------------
CPU: Athlon XP 2200+ M (FSB 200/266 MHz)
RAM: 256 MB DDR 266 (checked with memtest86+ for 35 hours)
Graphics: S3 ProSavage8 KM266/KL266 (Xorg driver "savage")
Chipset: VIA Apollo Pro266 AGP (memtest86+ prints "VIA KN266")

Desktop hardware:
-----------------
CPU: Athlon XP 1800+ (FSB 200 MHz)
RAM: 256 MB DDR 200/266
Graphics: Nvidia GeForce2 GTS (Xorg driver "nv")
Chipset: VIA Apollo KT266A

2) On the same laptop (with 256 MB of memory) Debian Woody and Sarge
(both with kernel 2.6) ran stable and fast for about 20 months.
Instability and bad performance occured after migration to Ubuntu.

Is there a different memory management between Ubuntu on desktops
and Ubuntu on laptops and between Ubuntu and Debian in general? I'm
not a programmer so my question may be stupid. I just observed the
things above and I'm very astonished.

Best,
  Christoph

[1] http://permalink.gmane.org/gmane.linux.ubuntu.user/59879
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