Killing Mac OS X Swapping : How To Disable dynamic_pager

If like me you cannot deal with the swapping in OS X, and if you have tried everything possible, even not to launch dynamic_pager (and you've seen that you're system is not usable anymore (on my mac the 2Gb was detected but the system was refusing to use more then 1Gb )), then I have the solution : create another dynamic_pager that fits your needs

Actually, the original source code of dynamic_pager can be found at http://www.opensource.apple.com/darwinsource/10.5.2/system_cmds-433/dynamic_pager.tproj/dynamic_pager.c. You will need an apple developper account (that's free) do download it. If you know how to compile this, please add a comment to this post.

After a bit of hacking, (removing cryptic junk, calls to private code of the kernel that is not accessible for the public, hacks to make it compile and commented a macx_swapon call), here is the modified dynamic_pager.c. Once you downloaded it it can be compiled by using this awful command :

gcc -o dynamic_pager -no-cpp-precomp -DNO_DIRECT_RPC -framework CoreFoundation -framework IOKit -lSystem.B -R -DNO_DIRECT_RPC dynamic_pager.c -I/Developer/SDKs/MacOSX10.4u.sdk/System/Library/Frameworks/Kernel.framework/Versions/A/Headers -I/Developer/SDKs/MacOSX10.4u.sdk/usr/include


Then (after having done a backup of the regular dynamic_pager) copy your brand new dynamic_pager to /sbin. Reboot and enjoy : it will only create a single swap file (64Mb), no less, no more.

I'm currently running it and it seems to work really fine. All my memory is used, not only the first 1Gb. The Inactive Memory is high as usual, but the single swap file is only marginally used.

The code posted above is just a big hack, when I will have more time I will clean up the code so that it will be a bit more understandable.

Enjoy.