New to Macs - Memory question

Discussion in 'iMac' started by BasilFawlty, Jul 9, 2011.

  1. BasilFawlty macrumors 6502

    BasilFawlty

    Joined:
    Jun 20, 2009
    Location:
    New Mexico
    #1
    Just bought a new 27" i5 and was looking at the activity monitor. Specifically, the memory tab lists the following types of memory and shows how much is associated with each type (pie chart):

    Free
    Wired
    Active
    Inactive
    Used

    How are these defined?
     
  2. BasilFawlty thread starter macrumors 6502

    BasilFawlty

    Joined:
    Jun 20, 2009
    Location:
    New Mexico
  3. johnfkitchen macrumors regular

    Joined:
    Sep 7, 2010
    #4
    The pie chart is potentially very misleading, because it's just a point in time measurement of RAM allocations. RAM demand fluctuates wildly at microsecond intervals, and you are seeing updates maybe once a second.

    The key metric is Page Outs. If it's zero, you have always had enough RAM since you last booted. If you are seeing spinning beach balls, then it's not being caused by RAM shortage.

    If it's not zero, there have been times when you have run out of RAM. If you are seeing beach balls, the cause MAY be lack of RAM.

    If you have an SSD as a boot drive, your system can tolerate much higher page rates than if you use an HDD.
     
  4. BasilFawlty thread starter macrumors 6502

    BasilFawlty

    Joined:
    Jun 20, 2009
    Location:
    New Mexico
    #5
    Thanks for the additional info - my Page outs are zero, but that's not surprising as I have not done much but surf and email since last boot-up. Nice to know that's a way to tell if my current memory is sufficient.
     
  5. MacUser2525 macrumors 68000

    MacUser2525

    Joined:
    Mar 17, 2007
    Location:
    Canada
    #6
    Does not tell the whole story though what you really want to look for is the ratio of page ins to page outs if it is even or less than 1 then you would want more ram if it is a good multiplier then you do not need more ram for instance mine is 17m in 400k out or roughly 42 to 1 so no need for more ram.
     
  6. alust2013 macrumors 601

    alust2013

    Joined:
    Feb 6, 2010
    Location:
    On the fence
    #7
    The ratio really isn't that relevant. Say, if you're doing editing and you're paging in massive amounts of data, take 1 TB for example, but you're paging out even 1/40th of that (25GB), you're going to have problems. When you're paging out a few megs, it really won't matter. You want to minimize page outs regardless of what your page ins are.
     

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