How 64-bit Snow Leopard Will Improve Performance

AppleInsider has posted an in depth examination on how much memory a specific app can use and how performance will improve with 64-bit addressing despite the additional overhead involved.

While the 4GB limit described earlier is only just beginning to affect mainstream users, there's another problem that prevents full use of the installed memory by any specific application. In fact, the real problem for RAM-starved apps is not how much RAM can be installed in a machine, but rather the limits on the amount of memory a single application or process can address itself.

The 32-bit versions of Windows, Linux, and Mac OS X handled their 4GB limit differently. That means their transitions to 64-bits offer varying levels of improvement to their users. In 32-bit versions of Linux and Mac OS X, the kernel maps out a 32-bit, 4GB virtual memory space for itself and one for each app (or process). The virtual memory system shuffles memory around as needed to take best advantage of however much RAM is installed. The more RAM the better, of course.

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