[1737] in RedHat Linux List
Cleaning up memory space after something goes awry
daemon@ATHENA.MIT.EDU (Ariel Mazzarelli)
Wed Oct 30 01:00:59 1996
Date: Tue, 29 Oct 1996 19:48:16 -0800
From: Ariel Mazzarelli <mazzare@primenet.com>
To: redhat-list@redhat.com
Resent-From: redhat-list@redhat.com
Reply-To: redhat-list@redhat.com
Five minutes ago, I made an excessive request to ghostscript, and after making
my hard drive hum for a couple of minutes, the box coughed
[mazzare@va tempy]$ Error: Cannot perform malloc
and ghostscript left the premises. No biggie, it's not like I have to reboot
or anything, but I noticed that the swapping continued after that (though not
really slowing things down much). Here is what the free command says,
[mazzare@va /home]$ free
total used free shared buffers
Mem: 31084 30572 512 4108 1744
-/+ buffers: 28828 2256
Swap: 32980 32944 36
which makes me wonder about this swap thing in general. I have noticed that
the "used" column for swap is 0 after a reboot, but after a while, it acquires
a residue, usually in the 2 meg range. Sometimes it will hover at something
well over 2 megs while I am in an X session, and when I return to the login
shell most of that is gone (except for the 2 meg residue).
These phenomena, coupled with my general ignorance, brings up a few questions:
Does one want to see that "used swap" column reach 0, or do we simply not care?
I remember reading an ancient LJ article, possibly written by a distinguished
member of this very list, that explained that it was actually the "free"
column that should not be very high, as "free" was close to "wasted". OTOH,
it sure seems like the system drags its feet when that "free swap" entry
gets low. We like big buffers, I suppose.
When something goes awry, is there something less drastic than a reboot that
one may do to get rid of residual effects (e.g. excessive swapping)?
What are some of the clever things that Linux does to handle memory resources
wisely--e.g., why does the same hardware that more or less flies under Linux
behave like a constipated pig under other more famous o$'s? That "shared"
column is part of the cleverness, as apps that use the same stuff get to
share it in memory space (to the extent that that is a safe thing to do).
What are some of the other clever things being done with RAM?
Ariel
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