What are the benefits of 64-bit computing?

In depth review of Snow Leopard should you care to read the whole thing, but this page http://arstechnica.com/apple/reviews/2009/08/mac-os-x-10-6.ars/5 covers off the 64-bit information.

Actually, the 32-bit kernel is quite capable of handling more then 4GB of memory, as it has for years on Mac Pro's and XServe's.

The issue is how much memory the kernel itself has to work in. A 32-bit kernel can only use 4GB of RAM for itself and all the memory it manages. Managing the address space for system memory itself takes up RAM, as the kernel has to keep its page space file in memory. That means that as you install memory beyond 4GB for applications, the 32-bit kernel has to use ever more of its 4GB limit just to keep track of all that extra memory space. That gets inefficient as total installed RAM gets big (like 64GB or more).

The 64-bit kernel itself can access 16 exabytes of RAM, so it has relatively unlimited resources to handle large memory installations.

At my work, we have a Dell Xeon (4xquad-core) machine with 128GB or RAM. If running a 32-bit kernel to manage that, the kernel itself would be using half of its available RAM just to map the memory page space for applications. Running a 64-bit kernel (Linux, in this case) means that the kernel can manage all that RAM without getting cramped for other kernel process RAM.

Right now, Apple machines really do not gain a whole lot from the 64-bit kernel, because so few of them have more then 4GB RAM in the first place. And so much of the software we all typically use is not written to take advantage of 64-bit memory space. That's changing for sure, and OS X 10.6 is, IMO, really Apple's attempt to make sure that their OS is positioned to take advantage of hardware and software before it comes mainstream (as opposed to playing catch up afterwards).

Are you asking for the benefits of 64-bit computing, or the benefits of Snow Leopard? If you are using Leopard, you can already run 64-bit apps (as long as your MacBook has Core 2 Duo). The kernel is 32-bit, but you can run 64-bit apps. Even with Snow Leopard, users of almost all Macs are running the 32-bit kernel by default, at least for now.

The benefits of Snow Leopard go far beyond 64-bit capability. The 64-bit capability will come into play much more, with new hardware that go beyond 4GB of RAM as the stock (low-end) configuration, and consumer-level software that actually needs to access more than 4GB of RAM on a regular basis.

Apple is just setting the pieces in place for the future. For most of the current and past Intel Mac hardware, 64-bit capability is probably not that significant. But Snow Leopard is significant for users of all Intel Mac hardware.

I think that the ram advantages of 64 bit computers is just a minor issue with most existing Mac computers. The average user today has between 2 to 8 GB's of ram. This amount of ram is easily handled by existing OS's like Leopard.

I believe that the actual benefits for most users will be when the code of their applications is re-written to run in 64 bit code.

From Apples Page on New Technologies: "It can also enable computers to crunch twice the data per clock cycle, which can dramatically speed up numeric calculations and other tasks." And on the same page: "64-bit applications can use more advanced security techniques to fend off malicious code".
http://www.apple.com/macosx/technology/

The 'twice the data per clock cycle' will affect all users regardless of how much ram they have or plan to buy for their machines. More data per cycle means more speed. Better security built into the OS is always a plus.

This is why a MBP with a 3GB limit will still want to run a 64 bit application, and my new iMac with an 8GB limit will still benefit from Snow Leopard.

I view all this extra memory abilities as something very far off for Mac users today. Ram prices will have to go down even lower, new machines will have to be bought with new ram management chips, etc.

Meanwhile, most of Apple's applications are currently running in 64 bit even if the Kernal is running at 32 bit, and other companies (like Adobe) should be coming out with 64 bit versions of their applications. Most experts agree that since the Kernal runs very low-level functions, it won't benefit from 64-bit operation near as much as user applications.

The big delays here, are for hardware drivers to work in 64 bit, and also for helper applications like Flash. Apple knew this going into the SL project. It's going to take a year or so until almost all of our programs are upgraded. Meanwhile, both 32 bit and 64 bit programs will run on Snow Leopard.

Message was edited by: dechamp