• Uknown (10/10) Aug 24 2018 I was messing and tried comparing the performance of different
• Peter Alexander (4/7) Aug 24 2018 n = 100 is too small to see parallelism gains.
• Uknown (4/11) Aug 24 2018 I was using n = 10000 originally, I reduced it because that

Uknown <sireeshkodali1 gmail.com> writes:

I was messing and tried comparing the performance of different 
ways to compute the factorial of a number. Here's the benchmark 
results:

recursive:	244 ms, 283 μs, and 2 hnsecs
loop:		241 ms, 412 μs, and 3 hnsecs
parallel:	1 sec, 784 ms, 829 μs, and 5 hnsecs


https://run.dlang.io/is/uyVlqu

I was quite surprised by the fact that parallel ran so much 
slower than recursive and loop implementations. Does anyone know 
why?

Peter Alexander <peter.alexander.au gmail.com> writes:

On Friday, 24 August 2018 at 13:04:47 UTC, Uknown wrote:
 I was quite surprised by the fact that parallel ran so much 
 slower than recursive and loop implementations. Does anyone 
 know why?

n = 100 is too small to see parallelism gains.

Try n = 10000

https://run.dlang.io/is/XDZTSd

Uknown <sireeshkodali1 gmail.com> writes:

On Friday, 24 August 2018 at 20:43:46 UTC, Peter Alexander wrote:
 On Friday, 24 August 2018 at 13:04:47 UTC, Uknown wrote:
 I was quite surprised by the fact that parallel ran so much 
 slower than recursive and loop implementations. Does anyone 
 know why?

 n = 100 is too small to see parallelism gains.

 Try n = 10000

 https://run.dlang.io/is/XDZTSd

I was using n = 10000 originally, I reduced it because that 
wasn't running on run.dlang. Tried this again on my machine and 
you were right.