The future of OS X - 32 bit vs. 64 bit

Discussion in 'macOS' started by CDN, Aug 8, 2006.

  1. CDN macrumors newbie

    Jul 27, 2006
    Hi all,

    I have a MBP, 2.16 GHz Core Duo. To the dismay of many, a Core 2 Duo MBP upgrade was not announced on Monday, but we all know that it's just a matter of time, and not too much of it.

    Leopard will be optimized for the new 64-bit Intel processors that have recently been released . . . my question for everyone is how much of a decrement in performance do you believe will be incurred by running Leopard on a Core Duo, 32-bit processor, rather than on one of the more recent 64-bit chips. I'm not familiar with the technical aspects of this issue and so am hoping for any input from the more Mac-Savvy of you guys (and gals).

    Many thanks,
  2. VanNess macrumors 6502a


    Mar 31, 2005
    None. 64 and 32 bit run side by side with no emulation.
  3. ham_man macrumors 68020


    Jan 21, 2005

    I think he's asking if Leopard will be faster on 64 Bit rather than a 32 Bit machine...
  4. projectle macrumors 6502a

    Oct 11, 2005
    In the big scheme of things, it is a definite kind of...

    Leopard will run faster doing high level mathematical calculations such as image editing, video editing, and database manipulation due to additional register width allowing for more complex tasks that can not be run in a single cycle in 32-bit to be condensed to a single operation.

    In most cases, you will not see this kind of performance increase in an operating system though (from a usage perspective) due to the fact that drawing a GUI does not really take that much effort on the CPU or Graphics Cards.

    So, for normal stuff, you should not see a difference.
    If you run an Oracle database on your system, and it is sufficiently large, you will probably see a good 30-40% performance increase (based on testing done under SuSE Linux 10.0 x86 32-bit & 64-bit with same data set).

    Odds are that Photoshop will not see this kind of performance increase because editing individual frames does not take that much register width.

    Editing something in FCP on the other hand should run significantly faster due to the ability to handle raw frame data plus frame manipulation in a single step (rendering video + color correction w/ some effect).

    64-bit is really only faster at the extreme end of the scale.
  5. projectle macrumors 6502a

    Oct 11, 2005
    As far as Leopard's support for 64-bit, under 64-bit hardware everything will run as 64-bit as apposed to what happens in Tiger where you have a 32-bit kernel and a 64-bit userspace sandbox to run specialized applications. This applies to Core2Duo's, Xeons and G5's.

    Leopard will also run entirely as 32-bit under 32-bit hardware like the CoreDuos, G4's and G3's. So, it will not need to emulate 64-bit in a 32-bit architecture to run the OS.
  6. Tehy macrumors regular

    Jan 15, 2006
    but how about the apps? Will 64 bit apps run on Core Duo or will there be two versions for 64 bit and 32 bit users?
  7. projectle macrumors 6502a

    Oct 11, 2005
    They are Universal Binaries. Apple has said that UB will allow for native 64-bit and 32-bit applications under the PPC and x86 Architectures in the same executable.

    So, no. There will not be different versions. One version that has the capabilities to run with each architecture's specific microcode and architectural enhancements.
  8. Mr. Dee macrumors 68000

    Mr. Dee

    Dec 4, 2003
    What I can't understand is the ability to run 32 bit software natively without the emulation layer such as a MOM64 - (32 Bit Mac OS on Mac OS 64), like WOW64 in Windows x64. Unless Leopard has a 32 bit compartment from which 32 bit drivers and 32 bit software load and run within their own memory space when executed, then again, it would still be an emulation layer from which it is running.

    Windows 32 bit apps run on Windows x64 at full speed with even a 9% boost in performance on certain apps, regardless its using an emulation layer to maintain compatibility. I guess its safe to say, Leopard does not support 16-bit apps, but did prior versions of OS X ever did in the first place?
  9. projectle macrumors 6502a

    Oct 11, 2005
    With Leopard, on 64-bit hardware, you are not running 32-bit applications, you are running 64-bit applications.

    A *.app file in OS X is really just a directory containing multiple files inside of it. In Universal Binaries, there are Intel executable files in there as well as PPC executable files.

    With Xcode 2.4 and Xcode 3.0, it puts PPC32, PPC64, x86, x86-64 in those folders so that they can run in native code execution rather than emulation.

    Lets create a hypothetical situation...
    You have a Powermac G4, it has Leopard on it. You decide to upgrade to a Mac Pro, you copy your program files directly from your applications folder to your Mac Pro's Applications folder, and your PPC 32-bit applications run immediately under your new system without rosetta as an x86-64 application with microcode optimizations to make it run as efficiently as possible.
    Hypothetical Situation Over

    The kernel knows what architecture it is running on and then sets an enviromental veriable that tells /usr/bin/open which one of those "files" in the *.app directory to open.

    As a visual aid, go to your Applications directory, CTRL-Click on an application (, for the sake of argument), and select "Show Package Contents".

    Look at all the stuff in there.
  10. risc macrumors 68030


    Jul 23, 2004
    Melbourne, Australia
    Isn't the point on universal binaries that there is only a single executable? If we take your example and have a look

    mbp:~ risc$ ls -l /Applications/
    total 680
    -rwxrwxr-x 1 root admin 347392 Jan 14 2006 Chess
    mbp:~ risc$

    there is only a single file.

    All it means is these new executable binaries will include support for 32 bit, 64 bit in both PPC and Intel flavours.
  11. LoveMacMini macrumors regular

    Jul 30, 2006
    as it stands right now i don't see operating systems taking advantage of 64 bit for atleast another 5 years.

    apple still ships computers with half a gig of ram, call me when the low end model has 4 gigs and then we can talk about the advantages of 64 bit applications and software.

    trust me, the computer industry is going bananas with adding cores, and you shouldn't be surprised at all to see a processor with 8 cores within 3 years. this multi tasking beast will need a lot of ram. a whole lot.
  12. Lollypop macrumors 6502a


    Sep 13, 2004
    Johannesburg, South Africa
    <strokes still usefull G3 mac> I think apple did a wonderfull thing with XCode, not only did they get the developers to create universal binaries but have them sneak 64bit apps in at the same time! Would there be a lot of work required to make sure that the 64bit segment of the code will run fully optimised or will xcode to that?

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