Re: Tunable overcommitting

Snow Cat (
Mon, 7 Apr 1997 09:49:22 -0700 (PDT)

Mikko J Rauhala once wrote:
> Greetings
> As we all know, there are two ways to get something implemented in the
> Linux kernel: Do it yourself or bitch about it on the kernel mailing
> list and hope that somebody does it. Here I am, doing the latter:
> Memory overcommitting is a relatively good idea in the world of
> memory-hogging software. However, sometimes the results are not too nice.
> Now, I was wondering that it'd be nice to have the maximum amount be
> tunable, for example via a /proc entry. The amount of overcommitting
> allowed could be presented in pages, so that the tuning is as
> fine-grained as possible throughout the memory area (so that you could
> disable overcommitting altogether or not to impose any limits). If the
> parameter would be changed and the overcommitting would already be
> higher than that, then all requests for more memory would fail until
> enough would be freed.
> Anyway, just a suggestion. Maybe, if nobody else will do it, I will look
> into it more someday when I have the time. Should learn some kernel hacking
> anyway...

Actually, memory hogs can control their own overcomittment by using
mmap() to allocate memory and passing MAP_NORESERVE to the pages that
they don't want checked.

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