Mongrel's memory usage

We've got a problem with a memory leak (we think) on our site. We've got monit running, which has helped the problem a lot by restarting mongrels when they get too bloated. But, this is obviously just a temporary solution while we try to find out whats really causing it.

I'm looking at mongrel on my local machine, and it seems that its general behaviour is to just keep on taking up more memory (for example, refreshing one of our pages over and over adds 10M to mongrel's memory usage each time!). Then, it gets to 207 meg and doesn't get any bigger whatever happens. (locally at least)

I don't know mongrel's workings very well at all, and i was wondering - is this 207 meg likely to be a setting for mongrel's maximum memory usage? And, before it hits this limit, does it never bother doing any garbage removal at all?

thanks, max