[SLL] Memory Leak Evidence from free, prompted by apache application use, but not cleared by apache restart

[Robert Woodcock]

On Wed, May 14, 2008 at 04:03:27PM -0700, Xeno Campanoli wrote:
> Actually, it looks like I do have 88 meg in swap, but that's pretty 
> minor these days...?  When we rebooted earlier though it had over a gig 
> in swap.  That was after the machine being up for months on end though, 
> and I never checked the swap from other things, so I don't have evidence 
> yet that the swap was from that program.

Note that modern (>= 2.2.x, I think) kernels do swap caching - that is, they
preemptively copy RAM into swap, so that if you do run out of RAM, the
kernel can immediately reuse any RAM that's already been copied out to swap
instead of waiting for it to be written out.

Many other OSs do the same thing (notably, Windows, which swaps out nearly
all memory used). On such operating systems, if you enable swap at all, you
should create as much swap space as you expect you might use for virtual
memory, without subtracting physical RAM.
-- 
Robert Woodcock - rcw at blarg.net
"Q: Do you know the name of the Defendant in this case?"
"A: I'm not sure. I'm just not sure."
	-- Jack Valenti, MPAA vs. 2600 depositions