Mac OS X 10.6 memory management: fixed
There are many reports across the web of OS X’s poor memory management, and up until yesterday, I had been suffering a lot because of it. However, finally, I’ve found the the cure! Something which I thought I would never do: disable swap.
What is “poor memory management” exactly?
In Linux, when physical memory is used up, swap starts getting used. However in Mac OS X (and Windows too), memory will be paged to disk even when there is free or inactive memory — and this sucks.
The solution: turn off paging to disk.
If you have enough memory to run all your day-to-day applications (I have 4GB), you can turn off the paging daemon to prevent OS X from paging anything to disk. For me, this has meant less disk thrashing and more responsive applications.
Turning off paging is something I thought I’d never do. In the past, I was completely against it as I trusted memory managers to make good decisions. However, since using Mac OS X 10.6, I no longer feel this way.
Here’s how you do it:
Paging is handled by a daemon called
dynamic_pager. Turn this off with launchctl:
sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.dynamic_pager.plist
sudo shutdown -r now
When the system boots back up, you can free some disk space by removing paging files:
sudo rm -f /private/var/vm/swapfile*
After this you’ll notice a lot more memory becomes “wired”, and memory is still marked “inactive” but it is freed straight away when other applications need it.