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SubjectRe: Overcommitable memory??
On 13 Mar 2000, Rask Ingemann Lambertsen wrote:

> > Ok, so my big gravitational simulation gets NULL from malloc and decides
> > to save it's work and exit. Uh-oh, time to demand-load a page of
> > executable code that had been discarded, so we can save the data. Hmm, but
> > we're out of memory...
> Without overcommit that just can not happen. There will be
> either a free page of memory or a free page of swap into which
> you can swap something else out.

Without overcommit it can still happen, unless you reserve one
page of swap space for every page of data that gets mmap()ed...

> Please realize that the only gain from overcomitting memory
> is that yoy may get away with having less swap space. The
> downside you get is random program crashes, lost work, etc.

Not really. Without overcommit you may still have random program
crashes and lost work...

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