The Solaris OS uses the SSE3 MONITOR and MWAIT instructions in the 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 the idle loop. MWAIT halts the processor until the address previously specified with MONITOR is accessed. With the new idle loop, a processor has to write to memory only to wake up a halted processor.