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Subjectvm in 2.4.5
Hi.

This is a little experiment to smash 2.4 vm, and there is something I do not
understand.

Experiment: compile a C file with, say, 100k lines of puts("test"), auto
generated. Box is running vanilla 2.4.5, on 256Mb of ram.

State before gcc tst.c (just logged in a Gnome session with a couple rxvt's
open):

werewolf:~> free
total used free shared buffers cached
Mem: 255688 99572 156116 0 6788 42876
-/+ buffers/cache: 49908 205780
Swap: 152576 0 152576

Start gcc tst.c, and used memory begins to grow linearly in time, until:

werewolf:~> free
total used free shared buffers cached
Mem: 255688 213856 41832 0 6788 42876
-/+ buffers/cache: 164192 91496
Swap: 152576 0 152576

Stays some moments this way, and suddenly both memory and swap are full:

werewolf:~> free
total used free shared buffers cached
Mem: 255688 251268 4420 0 3752 179948
-/+ buffers/cache: 67568 188120
Swap: 152576 152576 0

It does not begin to use swap in a growing fashion, it just appears full in
a moment.

When compiler (cc1) ends, and assembler starts, some mem is freed:

werewolf:~> free
total used free shared buffers cached
Mem: 255688 195784 59904 0 1708 178512
-/+ buffers/cache: 15564 240124
Swap: 152576 152576 0

And when all the gcc process ends, my mem ends up like:

werewolf:~> free
total used free shared buffers cached
Mem: 255688 191232 64456 0 1760 174628
-/+ buffers/cache: 14844 240844
Swap: 152576 152576 0

What process do belong the 150Mb of swap ???!!!!
Shouldn't that pages have been freed when gcc ends ?

In short, I begin in one state, gcc something, and I do not return to the
same state (I know it could not be the same, something has been paged out,
and still has not get in core again, but should not totals be roughly the
same ???). It looks like the files gcc has used are still cached and also
swapped out and reserved, or the like...

Perhaps this helps someone.

BTW, I do not understand what the hell for needs gcc 256 Mb to compile 100k
sequential sentences...

--
J.A. Magallon # Let the source be with you...
mailto:jamagallon@able.es
Linux Mandrake release 8.1 (Cooker) for i586
Linux werewolf 2.4.4-ac15 #1 SMP Wed May 23 21:55:23 CEST 2001 i686
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