But it's a real problem the "inactive" memory on OS X. If I do a malloc of 7GB with 6 GB free and 800 MB of inactive memory on my MBP, the system starts paging

But it's a real problem the "inactive" memory on OS X. If I do a malloc of 7GB with 6 GB free and 800 MB of inactive memory on my MBP, the system starts paging before it deallocates the inactive memory. If I ctrl-c the application, suddenly the active and inactive memory go down drastically, with inactive going to like 100 MB, so it obviously could have been given to the process wanting it before paging started.