Thorsten Froehlich wrote:
> 
> In article <jer### [at] cerebusacusdedu> , jer### [at] acusdedu (Jerry)
> wrote:
> 
> >Is there any way to tell the operating system in a dual-processor
> >environment to use both processors in floating-point operations? Does
> 
> There is no difference for processor between floating point and integer
instructions,
> the thread with *all* its instructions will be exectuted on the same processor. For
> todays processors (with built-in floating point units) there is *no* difference
> between floating point and integer or any other instructions.

I don't get what you mean.  There are separate machine instructions and
registers for floating point.  How is ther no difference.  Of course
I've never programed for an Intel.


> 
> >processor-switching occur fast enough for small operations like this to
> >speed up otherwise non-dual-supporting applications?
> 
> I suppose this is a typo and you wanted to write process-switching :-)
> Well, if there are two tasks each will run on a different processor (also this might
> depend on lots of there things).  As there are running lots of other tasks as well
> (like the Windows Explorer (the desktop), network services etc) and those are always
> there even on a single processor computer you will get a noticeable speed increase,
> if you have enough memory so no constant swapping is required you will see more than
> 50% speed increase when running two POV-Ray version at the same time. You can
> estimate the speed increase this way: Take one of the demo images that come with
> POV-Ray and that take a few minutes to render (the longer the rendering takes the
> more precise the measurement). Now render it when only one POV-Ray is running and
get
> the render time (this is time 1).  After that start a second POV-Ray and load the
> same scene file. Now prepare both POV-Rays for a render start. Start the first one,
> then (hurry!) switch to the second POV-Ray and start it as well. Wait after both
have
> finished and get the render times (these are times 2 and 3). How much faster was the
> rendering 1 compared to the _average_ of times 2 and 3. If rendering 1 took only
half
> the time of the average only one processor was used, if the average is near (perhaps
> 20% difference) time 1 you can be (nearly) sure both processors were used.
> 
>     Thorsten

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