redhat hang

If your RedHat system gets really overloaded and hangs here are some things that might help:

• SysRq: SysRq is a key combo you can hit which the kernel will respond to regardless of whatever else it is doing, unless it is completely locked up.
• Hangwatch: Hangwatch periodically polls /proc/loadavg, and echos a user-defined set of characters into /proc/sysrq-trigger if a user-defined load threshold is exceeded.
• NMI: Non-Maskable Interrupt (NMI) is a mechanism to detect system lockups. It enables the built-in kernel deadlock detector. By executing periodic NMI interrupts, the kernel can monitor whether any CPU has locked up and print out debugging messages as needed.