Processor Instruction Cycle Execution Time

Question

• My guess is that the __no_operation() intrinsic (ARM) instruction should take 1/(168 MHz) to execute, provided that each NOP executes in o

Answer 1

The number of clock cycles per instruction DO matter.

On an avr, its (usually) 1 instruction/clock, so a 12Mhz AVR runs at about 12 mips

On a PIC, its usually 1 instruction/4 clocks, so a 12Mhz PIC runs at about 3 mips

On an 8051 (orig) its 1 instruction/12 clocks, so a 12Mhz 8051 runs at about 1 mips

To know how much you can get done, instructions/clock are relevant. This is why an AMD processor could get more done /Mhz than an Intel processor.