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povray: Revised numbers


I love live peer review. No, I really do... ;)

If we're going to debate the relative quality of mainline and tree-ssa, it seems to me we need some real numbers. I'm an engineer, not a fortune teller.

Here are revised numbers for my povray test, based on comments both public and private:

                   compile  benchmark
                    time      time
                  --------  ---------
gcc mainline        1:43      7:59
  w/ -mfpmath=sse   1:46      6:30

gcc tree-ssa        1:46      7:35
  w/ -mfpmath=sse  ** SEG fault **

icc 8.0 1:53 5:50

Previously, I was unaware of the --disable-checking switch; using it to build tree-ssa improved its compile time such that it performs at the same speed as mainline.

Someone suggested privately that I try -mfpmath=sse with GCC; I hadn't had good results with that option on some other code, but I tried it just to see what would happen.

Mainline's code became *much* faster with -mfpmath=sse; however, tree-ssa generated a povray that segfaulted during picture generation. No, I have not had time to see if this is a known bug.

Mainline looks *much* better now; however, much as I want tree-ssa to move forward, I find myself concurring with many of Mark's views.

I may, if possible, run my Acovea program on GCC with povray, to see if I can find a set of switches that equal Intel's performance. I suspect, however, that most of Intel's advantage stems from its vectorization of code.


-- Scott Robert Ladd Coyote Gulch Productions (http://www.coyotegulch.com) Software Invention for High-Performance Computing



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