vm size?

Discussion in 'Mac Basics and Help' started by lmcintyre, Nov 9, 2006.

  1. lmcintyre macrumors regular

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    Jun 22, 2006
    #1
    what is vm? I think its virtual memory but the number seems high. Is this bad
     

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  2. Sun Baked macrumors G5

    Sun Baked

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    May 19, 2002
    #2
    Doesn't look like you've restarted in awhile ...

    Edit: Just a few pageouts there, hopefully that isn't a couple hours use.
     
  3. gr8tfly macrumors 603

    gr8tfly

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    #3
    Yep. It's virtual memory. It's dynamically allocated. My PB (160GB drive, 2GB RAM) currently shows 14.98GB. In a nut shell, VM helps the system use the physical memory efficiently. It allows the system to put the less frequently accessed data onto the harddrive, so tasks in the foreground or higher priority can use the fast, physical memory.

    The specifics of how it's allocated get pretty involved. I'm not sure I could sum it up well, here.

    Here's one technical document from ADC: http://developer.apple.com/documentation/Performance/Conceptual/ManagingMemory/Articles/AboutMemory.html
     
  4. SmurfBoxMasta macrumors 65816

    SmurfBoxMasta

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    #4
    your VM is high, and so are your pageouts.......because you are regularly exceeding your physical ram limits and the system is having to hit the HD for swapping of files back & forth

    This means you need more ram ASAP :)
     
  5. zetzulu macrumors newbie

    Joined:
    Nov 19, 2006
    #5
    vm

    Hi,
    I have the same question. My Mac pro came with 1GB, then I saw this page (VM) size of 9-12GB !

    I then bought 4 more to give me 5GB ram ... and the new VM size? Still 10 - 12. System startup 1 hour ago.
    This does not make sense, ok it may make sense on the implementation of this. Switching between apps is sluggish at times.

    Is there a way to control how VM is used ? (config file, hack, etc)

    regards
     

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  6. Fleetwood Mac macrumors 65816

    Fleetwood Mac

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    #6
    What programs are you running?
     
  7. bousozoku Moderator emeritus

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    #7
    It looks like you're running on a PowerPC machine that's been running a large variety of applications without re-booting for more than 30 days. Since you don't have much RAM, the system has to compensate by using disk space. Are you starting a lot of applications and you just leave them running all the time?

    There is no easy way to control the VM system. It would require understanding how it works and re-programming those parts of the base operating system.

    Actually, your statistics look better than most Intel machines I've seen because, even within a hour, they have many more page outs. The trouble is that Rosetta is there and it requires a lot of RAM to run efficiently. If you've got any PowerPC applications running, you might want to look for alternatives or minimise their usage.
     
  8. SmurfBoxMasta macrumors 65816

    SmurfBoxMasta

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    #8
    According to your stats, you are STILL using all but 60MB of your ram, and getting page-outs as a result. This is the source of the sluggishness.
    Adding more ram is the only way to solve this problem.

    The VM size wont necessarily go down that much just because you add extra ram. And NO, there is no practical way of controlling the VM allocations, short of reprogramming it.......
     
  9. WildCowboy Administrator/Editor

    WildCowboy

    Staff Member

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    #9
    He's got 3.5 GB of inactive RAM...he's got plenty of RAM. His page outs are fine.
     
  10. lmcintyre thread starter macrumors regular

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    Jun 22, 2006
    #10
    well i have a vm size 0f 13.30 GB and 1379298/631008 for page ins/outs. Is that bad? I am on an intel machine (mini) with no ppc apps firefox and adium are the only apps open.
     
  11. WildCowboy Administrator/Editor

    WildCowboy

    Staff Member

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    #11
    That's a fairly high ratio of page outs to page ins...you also don't appear to have restarted in a really long time. A restart might help clean things up a bit and make things feel snappier.

    Page ins and outs are one indicator of your RAM needs, but the true measure is whether your system feels sluggish, you get lots of beachballs, etc.
     
  12. SmurfBoxMasta macrumors 65816

    SmurfBoxMasta

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    #12
    His pag-outs are NOT fine, because once they start, they will get more & more......further reducing performance and increasing the sluggishness.

    Having 3.5GB of inactive ram doesnt mean squat if his machine is not utilizing it :)
     
  13. WildCowboy Administrator/Editor

    WildCowboy

    Staff Member

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    #13
    I disagree, but I don't claim to be the world's expert on RAM usage.

    It's virtually impossible to completely avoid pageouts, no matter how much RAM you have. There will be brief instances where your machine just is trying to do more than your RAM can handle. He's got a 100:1 page in-to-page out ratio. In my experience that's absolutely fine and nothing to worry about.
     
  14. zetzulu macrumors newbie

    Joined:
    Nov 19, 2006
    #14
    If you think adding more RAM is the answer, what would you say it is? Like I said I have 5GB now.... anything over 2-3GB is nice to have for hungry apps.

    I am trying to compare this to my linux (suse) system with 4GB ram. I tried loading it with apps and processes ... no swap on -in or -out ever gets used.

    On the MacPro - I checked all the app types as asked above and I only have 1 PowerPC app running. Interesting is that "kernel_task" uses 94MB real mem. and 1.85GB VM.
    I also do not understand why rebooting is so important ... seems like there is a 'memory leak' in the kernel or apps if you have to do this. ... suse has been up for 30 days (short), sorry for having to keep referring to the other *nix.

    New to mac so, just want to know ...
     
  15. bousozoku Moderator emeritus

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    #15
    That's pretty amazing for an Intel machine, from what I've seen so far. Most of them I've seen have page outs higher than the page ins.

    Yes, the page outs are okay as shown. It would be good to see it again in 24 hours to see if the page outs have exceeded the page ins. I suspect that they won't and there will be more free memory and less inactive memory.
     

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