Re: Poor performance with GNAT-GPL-2017

[Robert Eachus <rieachus@comcast.net>]

Doing some simple arithmetic:

> gnat-gpl-2017
> 
> $ ./bin/tangle 
> using:  8 tasks    duration 851 ms x 8 = 6.808
> 
> $ ./bin/tangle -t4
> using:  4 tasks    duration 1.213 ms x 4 = 4.852
> 
> $ ./bin/tangle -t2
> using:  2 tasks    duration 2.346 ms x 2 = 4.692
> 
> $ ./bin/tangle -t1
> using:  1 tasks    duration 4.638 ms x 1 = 4.638
> 
> 
> gnat-gpl-2016
> 
> $ ./bin/tangle 
> using:  8 tasks    duration 430 ms x 8 = 3.440
> 
> $ ./bin/tangle -t4
> using:  4 tasks    duration 740 ms x 4 = 2.960
> 
> $ ./bin/tangle -t2
> using:  2 tasks    duration 1.428 ms x 2 = 2.856 
> 
> $ ./bin/tangle -t1
> using:  1 tasks    duration 2.835 ms x 1 = 2.835

The numbers indicate that tasking overhead goes up with more tasks, but it also seems that the 2 to 1 ratio holds true.

Choices are: stick with the 2016 version, accept the slowdown, or buy an ACT subscription.