1 Reply Latest reply on Jan 18, 2012 6:26 PM by hazeman

    Clock cycles for various DP operations on 7970?


      I need to do some back-of-the-envelope comparisons of how fast an AMD 7970 can perform various double-precision operations, vs. an Intel Sandy Bridge processor.

      Anyone know where I can find that info for the 7970?



        • Clock cycles for various DP operations on 7970?

          On ATI cards all ALU SP operations take 1 cycle. DP precision is 1/4 of SP speed. But when you compare to CPU you should know that GPU supports only basic DP operations:

          mad, mul, div*, add, sub, SP->DP conversion, DP->SP conversion, ldexp, frexp

          *GPU has implemented reciprocal function with reduced accuracy. So for true 1/x ( or division ) you must add few mads.

          More advanced function like sin, exp, cos, log .... must be computed using those basic ops. And in this case CPU has huge advantage. You can look into CAL++ sources for implementation of few of those functions.