I realized the other day that on OS X, the Spotlight indexing process is started using
launchd. This makes it very easy to modify the
launchd configuration script to insure that background indexing uses the least amount of CPU and I/O bandwidth possible.
Edit the configuration script by running this command as root:
# open /System/Library/LaunchDaemons/com.apple.metadata.mds.plist
You should find yourself in the Property List Editor application. Now add two keys at the top-level, one named LowPriorityIO, which is a boolean set to true, and another named Nice which should be an integer set to 20.
Now whenever the
mdworker processes to index recent changes to the file system, it won’t get in your way quite as much as before. (Without this change,
mdworker processes run at the same priority as user processes, according to output from the
ps axl command).