From: Ara.T.Howard@...
Date: 2005-06-22T06:30:36+09:00
Subject: Re: 1. Ruby result:  101 seconds , 2. Java result:9.8 seconds, 3. Perl result:62 seconds

On Wed, 22 Jun 2005, Michael Tan wrote:

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> Just new to Ruby since last week, running  my same functional program on the windows XP(Pentium M1.5G), the Ruby version is 10 times slower than the Java version. The program is to find the prime numbers like 2, 3,5, 7, 11, 13...  Are there setup issues? or it is normal?
> 1. Ruby result:  101 seconds
> 2. Java result:9.8 seconds
> 3. Perl result:62 seconds

if you just want a fast ruby version:

   harp:~ > cat prime_inline.rb
   def benchmark label, code
     STDOUT.sync = true
     puts "#{ '=' * 16 }\n#{ label }\n#{ '=' * 16 }"
     fork do
       GC.disable
       a = Time::now.to_f
       code.call
       b = Time::now.to_f
       puts " @ #{ b - a }"
     end
     Process::wait
   end

   prime_test = lambda{ (2 ... (2 ** 14)).each{|n| n.prime?} }

   class Fixnum
     def prime?
      (2...self).each{|i| return false if self % i == 0}
        return true
     end
   end
   benchmark 'pure ruby', prime_test

   require 'inline'
   class Fixnum
     inline do |builder|
       builder.c_raw <<-src
         static VALUE
         is_prime_c (int argc, VALUE *argv, VALUE self) {
           long i, n = FIX2LONG (self);
           for (i = 2; i < n; i++) if (n % i == 0) return Qfalse;
           return Qtrue;
         }
       src
     end
     alias prime? is_prime_c
   end
   benchmark 'inline c', prime_test

   harp:~ > ruby prime_inline.rb
   ================
   pure ruby
   ================
    @ 14.9205560684204
   ================
   inline c
   ================
    @ 0.539831876754761


so that's about two orders of magnitude speed-up for less than 10 extra lines
of code - and you still get nice things like overflow safety.

hth.

-a
-- 
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