How to disable Mac OS X from using swap when there still is "Inactive" memory?
Problem
A common phenomena in my day to day usage (and several other's according to various posts throughout the internet) of OS X, the system seems to become slow whenever there is no more "Free" memory available. Supposedly, this is due to swapping, since heavy disk activity is apparent and that vm_stat reports many pageouts. (Correct me from wrong) However, the amount of "Inactive" ram is typically around 12.5%-25% of all available memory (^1.) when swapping starts/occurs/ends. According to http://support.apple.com/kb/ht1342 : Inactive memory This information in memory is not actively being used, but was recently used. For example, if you've been using Mail and then quit it, the RAM that Mail was using is marked as Inactive memory. This Inactive memory is available for use by another application, just like Free memory. However, if you open Mail before its Inactive memory is used by a different application, Mail will open quicker because its Inactive memory is converted to Active memory, in…
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1 Fix
Fix for: How to disable Mac OS X from using swap when there still is "Inactive" memory?
By definition, inactive memory is memory that is ready to be paged out, and paging it out might involve writing it to swap. This is not any kind of problem or issue that should be optimized; it is in fact OS X working as designed. Unfortunately, tech support writers are not kernel developers, and the Apple Knowledge Base support article quote is just wrong when it claims that Inactive memory is memory unused by programs. When you quit a program, all of its resident memory becomes Free; it doesn…
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