Ideal Swap Partition Size

Patrick O'Callaghan pocallaghan at gmail.com
Thu Jan 22 22:28:13 UTC 2009


On Wed, 2009-01-21 at 17:53 -0800, Gordon Messmer wrote:
[...]

> The feature that you're referring to is called "overcommit".  I had
> hoped that by referring to it *by name*, I could avoid inaccurate
> corrections, but I guess not.
> 
> Overcommit uses a heuristic algorithm to determine whether or not a
> request to allocate more memory than is present (either by malloc or
> fork) will be allowed.  In many cases, fork() will fail if you do not
> have enough memory for a second copy of the application, even though
> Linux doesn't copy a complete set of pages during fork().  If you want
> the system to work *reliably*, you must have enough free memory for a
> second copy of your largest application.  In most cases you should
> achieve that by having at least as much swap as physical memory.

I see. I simply hadn't noticed the overcommit factor. Thanks for the
clarification.

poc




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