Virtual Memory Swap Page-in Page-out Question

Discussion in 'MacBook Pro' started by elberto1, Sep 10, 2012.

  1. elberto1 macrumors newbie

    Joined:
    Jul 28, 2012
    #1
    Hi Guys,

    I have a MBP with Retina Display (2.7ghz, 16gb RAM, 512gb SSD)

    I notice that even with VMWare running, I never have any page-outs in iStat. BUT I have over 6 million page-ins after just a few hours.

    Since my computer never uses the page-outs, I was thinking about disabling the virtual memory swapping (aka page file) in Onyx.

    If I never have page-outs, I feel that this will prolong the life of my SSD without any performance or stability negatives.

    Can someone advise if this is wise?

    Thanks!
     
  2. simsaladimbamba

    Joined:
    Nov 28, 2010
    Location:
    located
    #2

    Normally modern SSDs have a theoretical write/read limit of 10,000 to 100,000 cycles (P/E cycles), meaning if you had a 64 GB SSD and its cycle limit would be 10,000, you would have to write 625 TB to it, which would be 351 GB per day everyday for the next five years. Assuming those numbers vary and it would only be a tenth of that, it would still mean 35 GB per day, which under normal usage no average computer consumer does, not even with temporary files.
     
  3. Afbar1114 macrumors 6502a

    Joined:
    Jun 18, 2012
    #3
    i just looked at my page-ins it said 311 mb is this good or bad or should i see whats causing it?
     
  4. simsaladimbamba

    Joined:
    Nov 28, 2010
    Location:
    located
    #4
    No need to look at that, It never worried me in the past eight years, as it is not an indication of a slow down or any other malfunctioning something.

    Some additional info: https://discussions.apple.com/thread/3033663?start=0&tstart=0
     
  5. elberto1 thread starter macrumors newbie

    Joined:
    Jul 28, 2012
    #5
    Thanks!!!

    I have about 8 million page ins per day with no page outs.

    Will disabling virtual memory swap improve performance?

    If I never ever get page outs, could it hurt stability?
     
  6. throAU macrumors 601

    throAU

    Joined:
    Feb 13, 2012
    Location:
    Perth, Western Australia
    #6

    Your Mac has a VM subsystem for a reason. If you disable virtual memory, it will be forced to keep idle applications in memory - memory that could be used for active applications.

    Now, to throw another spanner in the works:

    VMware will tell your virtual machine itself to swap to disk when memory becomes low (VMware tools installs the "balloon driver" into the VM so that it can intelligently swap to disk without VMware swapping pages out that it might be using). So, even if your mac is not paging from within OS X, memory pressure can/will cause it to make the guest virtual machine page to disk.


    In short:
    Leave paging on - if you run vmware, turning it off won't stop you hitting disk anyway - backup your data and just use the machine as it is designed to operate :)

    If your machine doesn't need to page, it won't page. If it does and you have VM turned off, yes it can cause stability problems due to memory scarcity.
     

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