From: Jaypee <rf.oodanaw@...>
Date: 2005-03-30T15:19:46+09:00
Subject: Re: Ruby performance question

Jaypee a �crit :
> 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
Thank you for your comments. I'd like to clear the point about Windows 
XP SP2: It works well, I could run the script from a command line 
(former tests were done using Eclipse and rdt) and it took 7 minutes on 
a P4@2.6 Ghz + 1 GB RAM
As I happended to have access to those similar platforms in terms of RAM 
and CPU, I just wanted to compare them and have an idea of performances 
using Ruby.
J-P