Question about memory use in Linux
My Debian Woody box has 128Mb of RAM, and a 128Mb swap partition. Anyway, one
of KDE's utilities allows you to monitor how much RAM and swap memory the
system is using. With Netscape Navigator and Messenger open, along with KDE
(obviously) it was using about 120Mb (95%) of RAM and 12.5Mb (10%) of swap. I
understand that linux uses essentially as much RAM as it can because it is
there. Now, I opened up that colossal memory hog, WP9 for linux. The RAM
usage shot up to 99% (about 7Mb more) BUT the swap usage only went up by
.75Mb, and that took a little bit of time. There was still over 100Mb of swap
space left, so why didn't the system use more of it? I might have expected
the RAM usage to "settle down" once WP9 was up and running by transfering
some more of the memory load from RAM to swap but other than maybe .5Mb (of
the .75Mb increase, that is) it didn't - RAM usage was still in the 98-99%
range. Then I carried out another experiment - I opened up, in addition to
WP9, Quattro Pro, Paradox and Presentations. Quattro Pro had a nominal impact
but the other two together brought swap usage up to about 37Mb, or about 30%
of total swap space. RAM usage was still up at 98-99%. Then, shutting down
all 4 apps of WPO had an interesting effect - swap usage slipped by 3Mb but
RAM usage went below 100Mb, or 80%. And it more or less stayed that way.
A somewhat related question is there any point in having 128Mb of swap? If I
had had 64 instead would it still carry on as it does or would it have scaled
back the system's swap usage in some proportion? Likewise, would adding
another swap partition increase the amount of swap being used or just spread
it around some more?
--
David P. James
Third Year Economics
Queen's University,
Kingston, Ontario
http://members.home.com/dpjames/
The bureaucratic mentality is the only constant in the universe.
-Dr. Leonard McCoy, Star Trek IV
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