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What benefits are there to running a 64-bit Operating System?

I bought a small 256MB slice from slicehost and installed Ubuntu 10.04 64bit and wordpress on it. Performance was dismal as apache was eating up all my memory. Once I did some taming of apache and switched to fCGI things ran fine.

Next I rebuilt as a 32 bit server, and performance was much better.

What benefit would I get from a 64 bit server. Is it all about the memory?

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marked as duplicate by ThatGraemeGuy, mrdenny Jun 2 '10 at 21:56

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The major advantage is that you can allocate more memory to processes. There is a theoretical limit at 4 GiB/process in 32 bit systems (in practice there are both workaround and other limits on the memory a process can use).

64 bit systems use longer pointers and a different instruction set which can slow some applications down while speeding up others. They use slightly more memory. In practice there is not much of a noticeable difference, unless you are in the HPC field.

Drivers for 64 bit systems are getting mature. They have previously been a huge problem, especially for windows.

There are not really any strong reasons to go 64 or 32 bits unless:

  1. You are dealing with applications needing more then 2GiB or ram
  2. You are dealing with 64 bit applications
  3. You need drivers that are only mature in their 32 bit version

Most people default to 64 bit systems today.

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