From: Sven Johansson <sven_u_johansson@...>
Date: 2006-01-02T01:12:55+09:00
Subject: Re: A few questions of function and style from a newbie

Robert Klemme wrote:

> A simple test shows that there is indeed significant overhead attached to
> method invocations - if methods perform simple tasks.  The relative overhead
> of course depends on the work the method performs.  I for my part would
> always start with a modularized version and only inline methods if this is
> actually a cure for a performance problem.  There is a famous quote about
> premature optimization...

Heh. But how can we know if it premature unless we have an idea about
how inefficient method calls are? :) Nevertheless, you point is well
taken.

> #! /usr/bin/env ruby
>
> require 'benchmark'
>
> REP = 1_000_000
>
> def foo(n) 0 + n end
>
> Benchmark.bmbm(10) do |bm|
>   bm.report("direct") do
>     REP.times { x = 0 + 1 }
>   end
>
>   bm.report("method") do
>     REP.times { x = foo(1) }
>   end
> end
>
>
> Rehearsal ---------------------------------------------
> direct      1.188000   0.000000   1.188000 (  1.201000)
> method      2.156000   0.000000   2.156000 (  2.166000)
> ------------------------------------ total: 3.344000sec
>
>                 user     system      total        real
> direct      1.187000   0.000000   1.187000 (  1.217000)
> method      2.172000   0.000000   2.172000 (  2.234000)
>
> $ ruby -e 'puts 2.172000 / 1.187000'
> 1.82982308340354

Ah, interesting. And a fine exemple of how to use the internal
benchmarking support for us Ruby newbies. More to the point, it shows
that it isn't so bad - I was thinking of order-of-magnitude losses, and
here is merely a factor two or so, and that's for essentially empty
method bodies... it will do. :)

> Happy new year!

To you as well!
/Sven