x86: MONITOR and MWAIT CPU Idle Loop

This kernel functions enhancement is new in the Developer 9/07 release.

The Solaris OS uses the SSE3 MONITOR and MWAIT instructions in x86 processor idle loop. Using the SSE3 instructions in the processor idle loop eliminates the overhead of sending and receiving an interrupt to wake up a halted processor. MONITOR is used to specify a memory range to “monitor”. MWAIT halts the processor until the address previously specified with MONITOR is accessed. With the new idle loop a processor only has to write to memory to wake up a halted processor.