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Are there any performance drawbacks (CPU, Memory or IO) when running a 32-bit application on a 64-bit Linux?

My main concern is inefficient utilization of pointers and memory blocks.

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up vote 7 down vote accepted

Practically no.

Note though that 64 and 32 bit application don't share libraries, so running one instance of 32 bit application may cause loading of many shared libraries "again".

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They also can't access the region of memory beyond the 3.4 GB marker, but that's very likely less of a concern. – Shadur Jun 24 '11 at 6:39
OK this is exactly what I'm wondering about. AIUI, with 32-bit kernel you can't address more than ~2.7G memory in a single process. So when running 64-bit kernel with 32-bit userland, there's still a barrier but now it's a little bit upward at 3.4G? – lkraav Sep 4 '12 at 20:08

You may not feel any differences..

OS will do every thing for you. Just Main memory space due to Duplicate libraries and other functions and also some CPU cycles wil be wasted. It will not affect you until you are not a super user (means who runs a lot of programs simultaneously)

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Why? Could you please you support your claims with links? – Adam Matan Jun 27 '11 at 10:56

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