4月16日
Why I am not crazy about 64 bit desktop applications
64-bit computing has been around for some years now and it didn’t get a lot of traction, despite the efforts from hardware and software suppliers. I know the reason: few people really need to run 64-bit software on their desktops; even on the server side the picture is not so rosy.
From a software developer point of view, if you are not managing more than 2 GB of memory in your program, it doesn't make sense to go to 64 bits. Some people would go further and say that a 64-bit address space is only worth if you have a *single variable* that holds more than 2 GB of data by itself. This is a far cry from the jump from 16 to 32 bits. In the Intel 16-bit world it was a huge pain if you wanted to have variables holding more than 64 kb each - which any stupid program did have back then; 32-bits cured that.
If you have less than 2 GB of data in your program, the same 64-bit code is way larger and thus slower (takes more time to load from memory) and the memory operations themselves are slower. I would dare to say that there are very, very few desktop programs around that would benefit from going to a 64-bit address space.
I’ve heard people say that if you have to manage a large, multi-gigabyte file, such as a video file, a DVD image or even a PST/OST Outlook file, you could use a large variable. Yes, you could but I am not sure that there would be a benefit loading the whole thing into memory at once, even if it were virtual memory.
On the server side, where a single application is actually serving hundreds or thousands of users, there are more reasons to go to 64 bits, especially in the case of infrastructure products that will be around for several years like a database server.
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