is istat accurate?

Discussion in 'macOS' started by silverite, Jan 29, 2010.

  1. silverite macrumors newbie

    Joined:
    Jan 27, 2010
    #1
    Hello,

    I was just curious on how accurate istat is?

    I have recently downloaded istat pro and istat menues. And they are both giving me the same reading in the memory section, while my activity monitor is giving me quite a different reading.

    My istat monitor says that my 'wired' ram is at around 480 mb. My activity monitor in contrast is saying that I am using around 741mb.

    To test this a bit more - I downloaded MenuMeters. And for some reason - it was showing similarly to what istat showed in that I was using less 'wired' memory compared to what my activity monitor is telling me.

    So its either that these three cpu monitoring programs are wrong - or my activity monitor is wrong :p

    All in all its very weird. And was wondering of other peoples experiences with istat - if its actually accurate for them etc.

    Any insight or help would be appreciated. I hope I don't have some faulty like system giving me inaccurate readings. Thanks.
     
  2. MisterMe macrumors G4

    MisterMe

    Joined:
    Jul 17, 2002
    Location:
    USA
    #2
    You are thinking like a MacOS 9 or Windows 98 user. MacOS X is a preemptive multitasking multiuser virtual memory operating system. The OS allocates memory as needed. However uses all RAM available to it because "Free RAM is wasted RAM." Unlike the older cooperative multitasking operating systems, MacOS X does not rely on the user for control of memory allocation.
     
  3. silverite thread starter macrumors newbie

    Joined:
    Jan 27, 2010
    #4
    I just meant that istat says that I am using 480 mb of 'wired' ram while my activity monitor says I'm using around 741 mb of this 'wired' ram. All the other stats under memory are the same though.

    I was just confused about the different readings of the 'wired' ram was all :confused:.
     
  4. MisterMe macrumors G4

    MisterMe

    Joined:
    Jul 17, 2002
    Location:
    USA
    #5
    The point that I am trying to get across is that the result is meaningless. Presumeably "wired" RAM is just real RAM as opposed to virtual memory. The OS tries to use as much RAM as is available.
     
  5. scaredpoet macrumors 604

    scaredpoet

    Joined:
    Apr 6, 2007
    #6
    Activity monitor is including the RAM being reserved for use by your video adapter. If you subtract the Activity Monitor total from your iStat total, the result comes to about 256MB, which is the amount being used by your integrated video card.

    iStat isn't counting it because it and most other normal applications don't see that as standard RAM. System monitor does.

    Does that make iStat less accurate? Welll, that depends on how you look at it. All the other totals (active, inactive, Free) will be correct. It's only Wired RAM that will disagree, but at least it will consistently disagree by about 256MB.
     
  6. silverite thread starter macrumors newbie

    Joined:
    Jan 27, 2010
    #7
    Thanks I finally got it now.

    I was trying to find online why there would be a difference between the two but couldnt find a thread between different values showing on istat compared to activity monitor.

    I had no idea that the difference was my graphics card not being counted by istat.

    And yes I am a new mac owner :p

    Thanks everyone for helping :apple:
     

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