New MBPs - 32-bit VS 64-bit kernel, what is better?

Discussion in 'macOS' started by Xylian, Jun 3, 2010.

  1. Xylian macrumors member

    Sep 28, 2009
    I have a 15" i5 MBP and I've noticed that on these new machines OSX SL still defaults on 32-bit kernel (I think for third-party drivers compatibility issues)... My question is are there any benchmarks that shows if there are some performance gains forcing SL to boot with a 64-bit kernel? Which of the two kernels do you use?
  2. seb-opp macrumors 6502

    Nov 16, 2008
    Maybe its only a benefit if you're using huge amounts of memory in a 64-bit app? Maybe it would only make a difference in a couple of years when macs will support over 8GB of RAM

    Why not just leave it at default and wait until the next Mac OS revision which might use 64-bit as default
  3. Xylian thread starter macrumors member

    Sep 28, 2009
    I know I can live even if I have a 32-bit kernel ;), I just want to understand if there should be some benefits with the 64-bit one.. Maybe there is also something else, some other low-level kernel operations and data structures may be improve or loose some performance when going from 32-bit to 64-bit kernel..
  4. robbieduncan Moderator emeritus


    Jul 24, 2002
    On non-server machines there is no point running the 64-bit kernel. Which is why Apple default to not doing so. Your apps can still run in 64-bit mode and use >4Gb of RAM. The advantage is that you don't need 64-bit drivers or kernel extensions so all your hardware (and any apps that happen to use kernel extensions) still work.

    If you really want to run in 64-bit mode you can and it can be slightly faster.
  5. Xylian thread starter macrumors member

    Sep 28, 2009
    Thank you for the link, it was what I was looking for (at least it gives us some more info about 32-bit VS 64-bit)... I think I'll set it permanently to 64-bit if I have no problems with the Vodafone HDSPA USB dongle I'm using (I'd bet that it uses 32-bit drivers :confused:)..
  6. wilsonhaven macrumors member

    Oct 12, 2009
    Is there a difference in power consumption and heat generated between the 32 bit and 64 bit modes?
  7. gnasher729 macrumors P6


    Nov 25, 2005
    The truth is, you have lots of applications that could run either as 32 bit applications or 64 bit applications, and the kernel is just another (slightly unusual) application. The kernel doesn't actually do very much work itself, so it doesn't make that much difference whether it is 32 bit or 64 bit.

    On the Macintosh, there is no such thing as "32 bit mode" or "64 bit mode". Every application runs as a 64 bit application if the programmers wrote a 64 bit version, and your processor is 64-bit capable, which would be everything built around 2007 and later. And it runs as a 32 bit application if it doesn't contain 64 bit code, or if it runs on a 2006 Macintosh. The kernel doesn't make a difference.

    It's like buying a Ferrari and wondering whether the sales person drives to work in a Ferrari or on a bicycle; it doesn't make a difference to the speed of the car.
  8. celticpride678

    Feb 15, 2009
    Boston, MA

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