How to tell if you need more memory or not?

Discussion in 'Mac Pro' started by msmth928, Jul 22, 2009.

  1. msmth928 macrumors regular

    Joined:
    Jun 3, 2009
    #1
    This is probably a daft question - but how do you know when you need more memory?

    I have 3GB in my 2009 MP (Quad 2.66) and istat usually says I'm using around 70%, but in activity monitor 'real memory' used totals to about 730MB.

    When I run top in terminal I get this:

    Also, will Snow Leopard change things? Will I need less memory when that's installed?

    Finally, I guess Kingston memory is ok? It says it has thermal sensors, and I'm thinking I might as well get the 6GB kit -and- the 2GB module as that works out only £10 more than getting just 6GB from crucial (who don't mention the thermal sensors either!).

    :confused:
     
  2. lamadude macrumors 6502

    Joined:
    Jan 12, 2006
    Location:
    Brussels, BE
    #2
    As long as you don't hit 100% of memory usage, adding new memory won't change a thing (exept maybe when you install identical pairs of ram.)
    I wouldn't upgrade unless you start noticing that your computer starts to slow down because it is running out of memory.
     
  3. Loa macrumors 65816

    Loa

    Joined:
    May 5, 2003
    Location:
    Québec
    #3
    Hello,

    A good way to tell if you need more memory is to determine if your system makes a lot of "page-outs". A page-out happens when the memory is full and the system has to write non-critical memory to the hard-drive (placing it in standby).

    Page-outs will slow you down.

    To know if you have a lot of page-outs going on, launch Activity Monitor and select "System Memory" in the bottom part of the window. You will see a line with the total amount of pageouts.

    Now this is a hard value to interpret. Basically restart your system first, then use all the apps you regularely use, especially those that you think would require a lot of memory (photoshop, video & audio work, some games...).

    Once you've worked in all your apps, look at that page-out value. It should be a LOT smaller than your page-in. In theory the best value would be 0 page-outs, but it's not quite possible to always have 0.

    After a few hours of work it should be very small, but it will grow to bigger and bigger values until you restart.

    The ratio between page-outs and page-ins is important. You should have a very small out / in ratio.

    If that ratio is not small, then more memory will be useful.

    Loa
     
  4. msmth928 thread starter macrumors regular

    Joined:
    Jun 3, 2009
    #4
    Thanks Loa - that's a very good post!

    I've had a quick look and currently mine are showing:

    Page-ins: 1.18GB
    Page-outs: 292MB

    How does that sound to you?

    Additionally it's saying:

    Free: 84.24 MB
    Wired: 544.68 MB
    Active: 1.62 GB
    Inactive: 785.57 MB
    Used: 2.92 GB
     
  5. iBookG4user macrumors 604

    iBookG4user

    Joined:
    Jun 27, 2006
    Location:
    Seattle, WA
    #5
    Ideally you'd want to have 0 Page Outs, so more RAM would help you. If you could manage it I'd add another 3GB to continue to take advantage of the triple channel capabilities. Since you have the quad, that would mean getting 3x2GB RAM instead of adding 3 more 1GB RAM.
     
  6. cube macrumors G5

    Joined:
    May 10, 2004
    #6
    You don't look at the paging totals. That means nothing.

    Run 'top' in the Terminal and look at the instantaneous paging while running the workload you care about (the numbers in parenthesis).
     
  7. Loa macrumors 65816

    Loa

    Joined:
    May 5, 2003
    Location:
    Québec
    #7
    Judging by the pagein-out ratios: you really need more ram.

    Triple Vs Dual memory usage in the 2009 MP quad is a theoretical speed difference only. There are physical reasons why it won't matter much (memory speed and voltages), and a lot of bandwidth reasons why it will matter even less in most apps.

    Still waiting on the verdict for a 2009 octo, but for PS4 tests on a 2009 quad, check my post here.

    http://forums.macrumors.com/showthread.php?t=736539

    Basically: 8GB is faster - better than 6GB for PS4 right now. And my guess would be: it will be the same for nearly all apps.

    Loa
     
  8. Dr.Pants macrumors 65816

    Dr.Pants

    Joined:
    Jan 8, 2009
    #8
    Depends on your applications. Personally I think its alright, but that would be with a 32-bit application (that could, say, only use 3 GB of RAM at a time).
     
  9. 2002cbr600f4i macrumors 6502

    Joined:
    Jun 21, 2008
    #9
    When you start forgetting things. Duh! ;)

    Seriously though... If you're paging out a lot, then yes, you need more RAM.

    Snow Leopard might actually require LESS RAM because the binaries won't be Universal anymore, so they'll take up less space. We'll just have to wait and see.
     
  10. Loa macrumors 65816

    Loa

    Joined:
    May 5, 2003
    Location:
    Québec
    #10
    Which memory intensive apps are you using?

    Loa
     
  11. Dr.Pants macrumors 65816

    Dr.Pants

    Joined:
    Jan 8, 2009
    #11
    I think the amount of RAM change will be minuscule, if any, with the loss of universal;) Correct me if I am wrong, but I would imagine PPC code wouldn't get loaded into the RAM. If it did, it probably could be overwritten and nothing would happen to the program.
     
  12. Firefly2002 macrumors 65816

    Joined:
    Jan 9, 2008
    #12
    if you start forgetting things frequently, it's time to upgrade.

    Snow Leopard might use less RAM because of some of the optimization and removal of some optional features, but UB makes no difference, they don't load PPC code on Intel machines, rofl.
     
  13. OZMP macrumors 6502

    Joined:
    Feb 18, 2008
    #13
    page ins VS page outs in istat pro.(best dashboard widget ever!)

    if you have a significant amount of page outs(eg, more than say 25% of the page ins) you need more ram

    mine after running for a week:

    Page Ins: 1,134,969
    Page Outs: 441
     
  14. DoFoT9 macrumors P6

    DoFoT9

    Joined:
    Jun 11, 2007
    Location:
    Singapore
    #14
    1559080(137) pageins, 430113(0) pageouts, thats after 9 days uptime when im on holidays. think i need to upgrade??
     
  15. Ploki macrumors 68000

    Joined:
    Jan 21, 2008
    #15
    2 days uptime
    346720 / 13671
    but i do believe i could use another gigabyte or two.
     
  16. OZMP macrumors 6502

    Joined:
    Feb 18, 2008
    #16

    your at about 1/3, Is this on the MBP or iMac? Personally I would be looking at the max and putting that in. Macsales.com say they will ship to aus, or if the ram is same as pc stuff www.scorptec.com.au are awesome for service. avoid comp now and apple stores in australia. both are useless.
     
  17. OZMP macrumors 6502

    Joined:
    Feb 18, 2008
    #17
    I would leave it for now unless it obviously struggles, Snow Leopard might make you fill your slots differently :p

    If your activity monitor looks like mine after a week of use, then leave it as is. I am on 10.6, It is much better with inactive memory than 10.5
     

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  18. wpc33 macrumors 6502

    wpc33

    Joined:
    Jul 2, 2006
    Location:
    Vancouver, BC
    #18
    Page ins: 461.07 MB
    Page outs: 190.82 MB

    Damn! 34 hours of light use, with 4GB of RAM.
    Yeah, my computer is a suped-up paperweight these days, but you MP guys above me don't have much more RAM.
    Is the speed of the pc3200 memory the problem? Is there anything I can do about this(I'm not worried, nor holding my breath. I know what I own.)
    PS: My model only has 4 slots that take 1GB each, max!:p
     
  19. DoFoT9 macrumors P6

    DoFoT9

    Joined:
    Jun 11, 2007
    Location:
    Singapore
    #19
    haha thanks for the reply :p i have a MBP, its maxed out with 2GB of RAM. it cant be upgraded any further. i consider myself a pretty heavy user, this computer lags all the time (even when im on holidays), but being a uni student i cant upgrade because of lack of funds.. i study IT, so im pretty 'in the know' with all the jargon ;)

    a MacPro is difinately in order once the money starts flowing.
     
  20. Loa macrumors 65816

    Loa

    Joined:
    May 5, 2003
    Location:
    Québec
    #20
    Nope! :)

    Loa
     
  21. bearcatrp macrumors 68000

    Joined:
    Sep 24, 2008
    Location:
    Boon Docks USA
    #21
    This is very true. I have 18GB ram in my mac pro and when using iMovie, I still get a few hundred page outs due to its limitations using 3GB ram. Be glad when all apps are written in 64 bit. Probably in the next 10 years. :eek:
     
  22. Cynicalone macrumors 68040

    Cynicalone

    Joined:
    Jul 9, 2008
    Location:
    Okie land
    #22
    It is kinda funny and sad to get pages out when you have a lot of RAM. I still get pages out everyday with 32GB of RAM.
     
  23. OZMP macrumors 6502

    Joined:
    Feb 18, 2008
    #23
    Similar boat to me, I am doing an IT traineeship, but my laptop is work supplied, so my pro has to last me til october next year when my pay doubles, then i will be getting a new one as a tax write off :p cars soak up all my money anyway...

    back on topic-

    Given iMovie is written by Apple I would say it will be sorted by Snow Leopard... and if not it will be ready for iLife '10
     

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