64-bit Linux virtual memory limit?

wmnwmn · 02-01-2008, 09:38 AM

My application needs > 4GB of virtual memory, i.e. a single process needs to be able to malloc this amount. This seems to be impossible in 32 bit linux, but I am wondering if it is possible with 64 bits, in particular RHEL? If so, would I have to alter some system settings or would it be automatic?

Matir · 02-01-2008, 10:43 AM

In a 64-bit os, the maximum memory space for a single process is 2^48 bits. (More is theoretically possible, but no chipset on the market actually decodes more than 48 bits of address.) See: http://en.wikipedia.org/wiki/X86-64#..._space_details