Out of memory and overcommit_memory setting

[Antti Lankila]

Firstly, I'd want you to look at these two results from the following
command, executed one after other:

% time perl -wle 'sub foo { foo() } foo()'
Deep recursion on subroutine "main::foo" at -e line 1.
zsh: terminated  perl -wle 'sub foo { foo() } foo()'
perl -wle 'sub foo { foo() } foo()'  2,19s user 1,17s system 40% cpu 8,355
total
% time perl -wle 'sub foo { foo() } foo()'
Deep recursion on subroutine "main::foo" at -e line 1.
Out of memory!
zsh: exit 1     perl -wle 'sub foo { foo() } foo()'
perl -wle 'sub foo { foo() } foo()'  2,97s user 1,27s system 4% cpu 1:26,54
total

The difference between wallclock time between the runs is an
order-of-magnitude kind. What changed was that the avove (the one which was
running shorter) was run with overcommit_memory enabled, while the latter
(the one that took 1min 26s to recover) was running with overcommit_memory
disabled (which is the default setting).

However, I prefer the former kind of behavoiur. What gives? Why is it better
to run overcommit_memory enabed than disabled?

My kernel is 2.6.5-1-686 as packaged by Debian Sarge.

-- 
Antti
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