running a 32 bit binary on a 64 bit machine

Question

What are the implications if we are running a 32 binary on 64 bit machine.Will it have any impact if machine has more than 4 GB of RAM(the RAM in the system is 8GB)?

Answer 1

When running 32bit binaries on 64bit machines (assuming the OS is running in 64bit mode), you have the following limitations:

1. The binary cannot take advantage of 64bit arithmetic instructions. This might reduce performance.
2. The binary cannot address more than 4GB of virtual memory.

However, these 4GB can be located anywhere inside your 8GB of RAM. So if you are running many 32bit applications, each using less than 4GB, you do take advantage of all your 8GB of RAM.

Note that, due to various limitations, your application might actually only be able to allocate 2GB of virtual memory.