Question

Is there a simple way to compact the /var/vm/swapfile0 etc, short of rebooting?

They can get quite large if things start swap'ing, and my laptop doesn't have much free disc space..

Answer 1

As far as I know, the only way to force the /var/vm/swapfile* files to compact is (as you say) to reboot. I believe that more recent versions of OS X will compact these files automatically if enough memory is free and the system is idle. You could try closing some applications and waiting.

Answer 2

Not really. Swap files are important system files and should not be modified by the user.

For more clarification, check out this article:

By default, Mac OS X uses 80mb fixed sized swap files. It'll create additional swap files as needed. This is controlled by the /etc/rc script file which is run during boot. You can see the part near the end where calls dynamic_pager. By fiddling with the parameters, you can hose your machine. Or you can change the default sizes. I did this on a PowerBook (Wallstreet) with a very small hard drive to have a finer granularity. Using 40mb swap file size, when consuming 90mb of swap, only 120mb of disk space would be dedicated instead of 160mb. Not a big change, and not worth doing for most people. You could have it create a much larger file too.

Mac OS X can actually do swap object re-location and swap file removal. This actually is a pretty cool improvement from the ever expanding swap file problem under NEXTSTEP/OPENSTEP.

Answer 3

Mac OS X does remove swap files that it has dynamically created, if it no longer needs them.

I always find exiting/restarting Safari (or Firefox, if that's your browser of choice) tends to help...

Answer 4

Mac OS X really comes under pressure when you have less and less disk space, which can cause issues. I would suggest backing some data up and removing it. Also check out the Caches in your Library folder to make sure your programs are cleaning up after themselves.