Free vs inactive memory in iStat Pro

Discussion in 'Mac Apps and Mac App Store' started by maccanuck2006, Sep 21, 2007.

  1. maccanuck2006 macrumors member

    Joined:
    Aug 27, 2006
    Location:
    Vancouver Canada
    #1
    Hi all:

    I have iStat Pro 4.2 installed on my 2.4Ghz SR MBP. I am running 10.4.10 with 4 gigs of RAM. I keep my laptop on all the time and just put it to sleep inbetween active use. iStat Pro has shown that my "free" memory goes as low as 190 megs over time, with the "inactive" memory hovering between 2-3 gigs.
    Just for kicks I shut it down and rebooted; the "free" memory jumped up to 3.2 gigs; I'm currently monitoring it after opening and closing various apps to see what happens to it.

    I looked on the islayer website but the istat manaul doesn't say what the difference is between free and inactive memory with respects to performance; just that iStat differentiates the two. They do mention that inactive memory is sent back to cache while free RAM is just unused. However I'm not sure what that all means.

    Is a loss of "free" memory over time indicative of a memory leak in OS X, or is it completely irrelevant and unused RAM (Free and inactive) is all the same thing?

    BTW: I haven't noticed any perceptible performance hit over time with repeated sleeps.

    Thanks
     
  2. swiftaw macrumors 603

    swiftaw

    Joined:
    Jan 31, 2005
    Location:
    Omaha, NE, USA
    #3
    unused RAM = free + inactive

    Inactive memory is memory that has previously been used to run an application. OSX keeps certain things in memory just in case you launch the application again, so that it'll launch quicker. However, this inactive memory can be released to a new app as needed.
     
  3. maccanuck2006 thread starter macrumors member

    Joined:
    Aug 27, 2006
    Location:
    Vancouver Canada
    #4

Share This Page