14.3.16. BogoMIPS Value too low

Question:

We are only seeing 263.78 bogomips on a MPC5200 running at 396 MHz.
Doesn't this seem way to low ?? With a 603e core I'd expect 1 bogomip per MHz or better.

Answer:

No, the values you see is correct. Please keep in mind that there is a good reason for the name BogoMIPS.

On Power Architecture®, the bogomips calculation is measuring the speed of a dbnz instruction. On some processors like the MPC8xx it takes 2 clocks per dbnz instruction, and you get 1 BogoMIP/MHz. The MPC5200 takes 3 clocks per dbnz in this loop, so you get .67 BogoMIP/MHz.

See also The frequently asked questions about BogoMips.