Mienai <Mienai> wrote:
> Actual benchmarks have shown that if you run 2 instances of POVRay on a
> hyperthreading machine (one instance on each logical processor, each
> rendering half your image) you will have the completed image in around half
> the time (assuming the two halfs take about the same time to render).

  I find that hard to believe. Either that is not true, or the claim
that two processes can't use the FPU at the same time is not true.

  If I'm not mistaken, one POV-Ray thread could perform integer math
at the same time the other POV-Ray thread is performing FPU math. But
when the first one needs the FPU it has to wait for the second. Since
POV-Ray uses the FPU quite heavily, I find it quite hard to believe
that running it in two threads would drop the rendering time to half
(unless the P4 *really* can run two FPU threads at the same time).
  I am ready to believe that the total rendering time drops by
some percentage (because POV-Ray naturally performs other operations
than just FPU opcodes, naturally), but I would be surprised if this
percentage would be anything close to 50%.
  If it really is close to 50%, then someone has to explain me how
is that possible.

-- 
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -

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