Why is my inactive memory not getting free?

Question

When my MacBook Pro (13" 2010, Intel C2D 2.4 GHz, 4GB RAM 1067 MHz DDR3, running Snow Leopard) runs out of free memory, instead of releasing inactive memory (which is mostly about 500 - 1000 MB), it starts to write to disk (raising page outs).

Here are processes that are running on my macbook:

Active Memory: 1.64 GB
Free Memory: 1.04 GB
Wired Memory: 724.7 MB
Used Memory: 2.96 GB
Inactive Memory: 627.7 MB
Total VM: 176.36 GB
Number of processes: 82

PID    Process Name              User       CPU      Real Mem        Virtual Mem    
0      kernel_task               root       7.4      278.0 MB        2.56 GB          
1      launchd                   root       0.0      724 KB          2.34 GB          
10     kextd                     root       0.0      1.5 MB          2.34 GB          
11     DirectoryService          root       0.0      4.0 MB          2.34 GB          
12     notifyd                   root       0.0      564 KB          2.33 GB          
13     syslogd                   root       0.0      548 KB          2.34 GB          
14     configd                   root       0.0      2.6 MB          2.36 GB          
15     diskarbitrationd          root       0.0      748 KB          2.33 GB          
17     mDNSResponder             _mdnsrespo 0.0      1.5 MB          2.35 GB          
18     distnoted                 daemon     0.0      1.3 MB          2.33 GB          
21     securityd                 root       0.0      2.3 MB          2.35 GB          
22     blued                     root       0.0      2.6 MB          2.35 GB          
25     ntpd                      root       0.0      724 KB          2.32 GB          
26     cupsd                     root       0.0      1.1 MB          2.34 GB          
27     krb5kdc                   root       0.0      1.0 MB          2.33 GB          
30     usbmuxd                   _usbmuxd   0.0      2.2 MB          2.35 GB          
35     mds                       root       0.0      29.8 MB         2.59 GB          
36     loginwindow               mihal      0.0      5.9 MB          2.61 GB          
37     KernelEventAgent          root       0.0      528 KB          2.33 GB          
39     hidd                      root       2.5      996 KB          2.33 GB          
40     fseventsd                 root       0.0      1.7 MB          2.34 GB          
42     dynamic_pager             root       0.0      428 KB          2.32 GB          
48     autofsd                   root       0.0      536 KB          2.33 GB          
55     coreservicesd             root       0.3      9.0 MB          2.37 GB          
69     WindowServer              _windowser 4.5      112.2 MB        2.81 GB          
74     cvmsServ                  root       0.0      508 KB          2.33 GB          
86     coreaudiod                _coreaudio 0.0      3.1 MB          2.34 GB          
89     launchd                   mihal      0.0      1.3 MB          2.34 GB          
93     pboard                    mihal      0.0      372 KB          2.32 GB          
94     Dock                      mihal      0.0      29.6 MB         2.70 GB          
95     SystemUIServer            mihal      0.0      11.2 MB         2.70 GB          
96     Finder                    mihal      0.0      18.5 MB         2.73 GB          
105    fontd                     mihal      0.0      2.8 MB          2.38 GB          
112    UserEventAgent            mihal      0.0      4.1 MB          2.60 GB          
119    AirPort Base Station Agen mihal      0.0      3.9 MB          2.62 GB          
120    PenTabletDriver           mihal      0.0      5.3 MB          2.66 GB          
125    Folder Actions Dispatcher mihal      0.0      4.0 MB          2.62 GB          
129    Adium                     mihal      0.0      32.3 MB         1.08 GB          
131    Mail                      mihal      0.2      64.3 MB         3.75 GB          
132    TransmitMenu              mihal      0.0      6.6 MB          2.63 GB          
142    ConsumerTouchDriver       mihal      0.0      3.6 MB          2.62 GB          
143    TabletDriver              mihal      0.0      3.6 MB          2.61 GB          
160    DashboardClient           mihal      0.0      12.7 MB         947.3 MB         
161    DashboardClient           mihal      0.0      31.4 MB         3.70 GB          
167    Activity Monitor          mihal      7.7      48.4 MB         2.77 GB          
169    activitymonitord          root       0.4      1.7 MB          2.33 GB          
188    iTunes                    mihal      0.3      111.0 MB        1.33 GB          
195    iTunes Helper             mihal      0.0      2.9 MB          2.60 GB          
197    applepushserviced         root       0.0      4.4 MB          2.35 GB          
199    AppleSpell.service        mihal      0.0      6.3 MB          2.35 GB          
671    Xcode                     mihal      0.0      166.5 MB        11.94 GB         
827    Interface Builder Cocoa T mihal      0.0      5.3 MB          908.5 MB         
828    Interface Builder Cocoa T mihal      0.0      5.0 MB          775.6 MB         
830    Interface Builder Cocoa T mihal      0.0      3.5 MB          777.1 MB         
1100   appleprofilepolicyd       root       0.0      360 KB          2.32 GB          
1114   DTActivityServer          root       0.0      952 KB          2.35 GB          
1882   Instruments               mihal      0.0      397.8 MB        3.32 GB          
2273   AAM Updates Notifier      mihal      0.0      4.9 MB          930.3 MB         
2497   iOS Simulator             mihal      0.0      15.0 MB         1,001.7 MB       
2501   ubd                       mihal      0.0      5.7 MB          630.6 MB         
2503   mediaremoted              mihal      0.0      6.0 MB          663.9 MB         
2504   locationd                 mihal      0.0      8.6 MB          675.3 MB         
2506   BTServer                  mihal      0.0      5.4 MB          642.0 MB         
2508   aggregated                mihal      0.0      3.3 MB          621.9 MB         
2509   SimulatorBridge           mihal      0.0      8.6 MB          766.1 MB         
2510   apsd                      mihal      0.0      3.7 MB          640.5 MB         
2514   SpringBoard               mihal      0.0      33.3 MB         851.1 MB         
2804   Google Chrome             mihal      0.0      154.6 MB        1.28 GB          
2886   Google Chrome Helper      mihal      0.0      7.2 MB          972.1 MB         
3541   Google Chrome Renderer    mihal      0.0      35.8 MB         1.01 GB          
3944   PTPCamera                 mihal      0.0      6.1 MB          2.63 GB          
3945   ath                       mihal      0.0      2.6 MB          2.35 GB          
3946   AppleMobileDeviceHelper   mihal      0.0      7.1 MB          2.35 GB          
3948   Image Capture Extension   mihal      0.0      6.5 MB          2.62 GB          
4048   VLC                       mihal      0.4      41.9 MB         2.73 GB          
4185   Google Chrome Renderer    mihal      0.0      40.4 MB         1.02 GB          
4187   Shockwave Flash (Chrome P mihal      0.2      27.0 MB         1.01 GB          
4192   Google Chrome Renderer    mihal      0.0      64.1 MB         1.05 GB          
4198   Google Chrome Renderer    mihal      0.0      32.5 MB         1.01 GB          
4200   Google Chrome Renderer    mihal      0.1      35.9 MB         1.01 GB          
4205   mdworker                  mihal      0.0      10.0 MB         2.36 GB          
4216   SFLIconTool               mihal      0.0      252 KB          2.31 GB

You do realize that your question is extremely generic and without access to the sort of processes that are running in your Macbook Pro, some hardware information and such, it would be close to impossible to answer this question, don't you? — Martin Marconcini, Nov 08 '11 at 20:21
no I don't... I thought that somebody had this experience before and could have at least an idea... but OK I will try to add some more information. Thanks — Michael, Nov 08 '11 at 20:26
we do our best to answer all the questions, but just mentioning that your inactive memory doesn't get released as free is impossible to guess out of nowhere. Try to be more specific. Thanks. — Martin Marconcini, Nov 08 '11 at 20:29
Are you asking out of curiosity or are you experiencing performance problems? — nohillside, Nov 08 '11 at 20:52
Performance problems...it's driving me crazy when I hear disk working and see how the system is so slow... I was using safari as my browser, and it was consuming too much memory and mostly I had page outs about 40% of page ins (I've read somwhere it should be less then 20%), so I switched today to chrome, which is more memory efficient, but still... this changes nothing about not getting inactive memory free — Michael, Nov 08 '11 at 21:02
now I've tried to run out of free memory by opening many tabs in chrome and as I was getting to zero of free memory, inactive memory even raised from 600 MB to 1000 MB and stayed so. And page outs of course raised too. How is this possible ??? — Michael, Nov 08 '11 at 21:29
and as I add even more tabs in chrome, it does nothing with inactive memory, just page outs are higher and higher, inactive memory still about 1 GB — Michael, Nov 08 '11 at 21:30
I'm not sure if this is going to help you, but there's an app on the app store called Free Memory. It frees your inactive memory so that might help you in this situation. — theAmateurProgrammer, Nov 09 '11 at 00:45
The comment system isn't a place to chat or add additional information to your question. Use the edit button for that, please. As for your memory problem, I don't think there is one. Inactive memory isn't freed when it's no longer being actively used. That's now how it works. Read Apple's support page for a better understanding: http://support.apple.com/kb/ht1342 Also you have provided nearly everything but your swap size (which would be huge if the system is behaving as you claim "poorly"). — , Nov 09 '11 at 02:57

score 3 · Answer 1 · edited Nov 09 '11 at 03:57

3

Well just in case you will load data from those inactive memory, things will get quicker. it's part of block replacement mechanism.

If you want to force it to claim back inactive memory, just $ purge . Xcode required.

edited Nov 09 '11 at 03:57

Nathan Greenstein

28,910

answered Nov 09 '11 at 02:39

Tuan Anh Tran

678

Why is my inactive memory not getting free?

1 Answers1

Linked