From: Jaypee <rf.oodanaw@...>
Date: 2005-03-28T21:39:53+09:00
Subject: Ruby performance question

Hello,

I am not a performance freak at all but I've noticed that despite a huge 
difference between a single CPU 1GHz G4 and a dual 2 GHz G5, both 
running ruby 1.8.2 with 1GB of RAM on Mac OS X 10.3.8, there was only a 
33% difference in the calculation of a factorial:
I used the following code:
#!/usr/local/bin/ruby
class Integer
   def factorial
     (1..self).inject(1) { |f, n| f * n }
   end
end

puts 100000.factorial

It takes about 9 minutes on the lower profile machine and 6 min or so on
the bigger one.

Generally, the generation of processor (G4 vs. G5) alone is responsible 
of a similar difference at equal clock frequencies. But here, I expected 
a bigger difference given the combined effect of a higher clock, a 
higher generation and a dual CPU.

BTW, I was not able to make a comparable test on my 2.6 GHz 1GB Windows 
XP SP2 workstation which failed at 9273.factorial. I don' t remember the 
message but it's easy to reproduce.

Is this kind of performance "normal" given the algorithm used or is 
there a balance between the coding style and the performances that could 
be wise to consider?

I have no performance objective, I am just curious.

Thank you for your advices,
Jean-Pierre