Every task or program that is performed on a system takes some time to process on the CPU. When the CPU has done all its tasks it is free and goes in a sleep mode.
Modern processors in this free time save power by reducing the speed of clock and the voltage of CPU and sending part of the processor in a sleep mode. Some processors have halt instruction that stops an idle CPU from saving power when an interrupt occurs. An example is the x86’s HLT instruction. By the time instruction is executed, the processor may save considerable amount of power and heat if the idle task is a loop that continually gives HLT instructions.
CPU Idle Loop’s Syntax:
