chrism@imntv.com wrote:
If you don't need to access greater than 4GB RAM, is there any benefit to running the 64-bit version of CentOS vs the 32-bit one? That's assuming, of course, that the target machine utilizes a 64-bit capable processor. I hadn't seen any noticeable difference, but I haven't done any benchmarking either.
Using AMD chips, 64 bit mode is significantly faster than 32 bit mode (20 to 30 percent, depending on the code), due to the extra registers. I don't think this is the case for Intel chips. We run all our 64 bit desktops in 64 bit mode, and it's not too hard to get closed source 32 bit apps working.
There are also advantages for things like LVM+RAID+XFS, as I believe the stack size is larger, so it's less likely to crash.
Also, consider that not all of 4GB of RAM can be used in 32 bit mode. The kernel takes up a large chunk of 4GB (depending on kernel compilation options), so this limits the amount accessed by a single process.
Jeremy