Ger wrote:

> Add to this the second time
> 58:50 = 3530
> makes a total of 7087 seconds
> 294912 / 7087 = 41.6 pixels per second
> which makes 66.06 / 41.6 = 1.59 speed factor
> 
> So a single instance is 1.59 times faster.
> 
> And the reason for this is that all non-Povray stuff is done by the other
> processor so Povray has one processor all to itself.
> 
I stand by my original conclusion. What matters to me is real live wall 
clock time from beginning of render to end. All 58 minutes of one render 
were within the 59 minutes of the other.

The single test starts (for instance) at 1:00:00 and finishes at 
1:37:12. The double test starts both instances simultaneously at 
2:00:00, and ends at 2:59:17 (when the second render finishes). It takes 
more time, but not twice as much time. When it is done, it has rendered 
twice as many pixels.

I like to do animations, so how I would generalize this is that the 
first render is running all the odd frames, and the second is running 
all the even frames. While it is true that it will take longer to run 
the odd frames simultaneous with the even frames than without, the total 
time for all the frames is less when simultaneous than when not.

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