On 11/24/10 11:06 PM, cpolish at surewest.net wrote: > http://www.centos.org/docs/4/html/release-notes/as-x86/ > Red Hat Enterprise Linux 4 includes a kernel known as the hugemem > kernel. This kernel supports a 4GB per-process user space (versus 3GB > for the other kernels), and a 4GB direct kernel space. Using this kernel > allows Red Hat Enterprise Linux to run on systems with up to 64GB of > main memory. The hugemem kernel is required in order to use all the > memory in system configurations containing more than 16GB of memory. The > hugemem kernel can also benefit configurations running with less memory > (if running an application that could benefit from the larger > per-process user space, for example.) that kernel will also greatly increase overhead of all system calls as they will require pagetable swaps on every transition from user -> kernel and back, and any arguments to kernel calls will have to be copied to a static shared buffer (and results copied back). large arguments will be particularlly ugly.