From: "Shot (Piotr Szotkowski)" <shot@...>
Date: 2009-11-03T21:46:50+09:00
Subject: Ruby Inline over two times slower under 1.9 than under 1.8?

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I=E2=80=99m starting to dip my toes in non-Ruby coding (for performance rea=
sons)
and began with looking at the (simplest) choice of Ruby Inline.

Interestingly, while my own number-crunching code seems to be generally
three times faster in Ruby 1.9 than in Ruby 1.8, the attached script
=E2=80=93 a slightly altered Corey Hoffstein=E2=80=99s example=C2=B9 =E2=80=
=93 seems to be actually
running its Ruby part slightly slower under Ruby 1.9, and over two times
slower when it comes to its C part:

$ ruby -v sort.rb; ruby sort.rb; ruby sort.rb
ruby 1.8.7 (2009-09-11 patchlevel 202) [x86_64-linux]
Ruby Time: 68.987515
Inline Time: 7.591179
Ruby Time: 67.758257
Inline Time: 7.371522
Ruby Time: 68.420539
Inline Time: 7.361452

$ ruby -v sort.rb; ruby sort.rb; ruby sort.rb
ruby 1.9.1p243 (2009-07-16) [x86_64-linux]
Ruby Time: 80.945370503
Inline Time: 17.813790662
Ruby Time: 75.493231541
Inline Time: 16.430632733
Ruby Time: 74.406748965
Inline Time: 17.018331102

What could be the culprit of this speed difference?

(Note that the C part is using the C++ Boost library =E2=80=93 but I doubt =
this
matters much, as the code is the same in both cases, and the resulting
=2Eso file seems to be interchaneable between the two Ruby versions.)

=C2=B9 http://coreyhoffstein.com/2009/06/16/sorting-with-ruby-rubyinline-an=
d-thrust/

=E2=80=94 Shot
--=20
ruby.about.com thinks =E2=80=98trollop=E2=80=99 is an inappropriate
name for a gem? Wait till they meet me in person.
                                   [William Morgan]

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# Ruby Sort Neighbors example=0A#  Take N random (x,y) points=0A#  For each=
 point, sort the neighbors!=0A=0Arequire 'rubygems'=0Arequire 'inline'=0A=
=0AN =3D 1_000 =0A=0Aclass Point=0A  attr_accessor :x, :y=0A=0A  def initia=
lize(x, y)=0A    @x =3D x=0A    @y =3D y=0A  end=0A=0A  def distance(other)=
=0A    Math.sqrt((other.x - @x)**2 + (other.y - @y)**2)=0A  end=0Aend=0A=0A=
def find_nearest_neighbors(point, neighbors)=0A  return neighbors.sort { |a=
,b| point.distance(a) <=3D> point.distance(b) }=0Aend=0A=0Aclass NearestNei=
ghbor=0A  inline(:C) do |builder|=0A    builder.add_compile_flags '-x c++',=
 '-lstdc++', '-I/usr/local/include/boost-1_39/'=0A    builder.include '<alg=
orithm>'=0A    builder.include '<vector>'=0A    builder.include '<boost/bin=
d.hpp>'=0A    builder.include '<cmath>'=0A=0A    builder.prefix '=0A      i=
nt distance(VALUE a, VALUE b, VALUE c) {=0A        double a_x =3D NUM2DBL(r=
b_iv_get(a, "@x"));=0A        double a_y =3D NUM2DBL(rb_iv_get(a, "@y"));=
=0A        double b_x =3D NUM2DBL(rb_iv_get(b, "@x"));=0A        double b_y=
 =3D NUM2DBL(rb_iv_get(b, "@y"));=0A        double c_x =3D NUM2DBL(rb_iv_ge=
t(c, "@x"));=0A        double c_y =3D NUM2DBL(rb_iv_get(c, "@y"));=0A=0A   =
     double b_dist =3D sqrt(pow(b_x-a_x, 2) + pow(b_y-a_y, 2));=0A        d=
ouble c_dist =3D sqrt(pow(c_x-a_x, 2) + pow(c_y-a_y, 2));=0A=0A        retu=
rn (b_dist < c_dist);=0A      }=0A    '=0A=0A    builder.c '=0A      VALUE =
find_nearest_neighbors(VALUE point, VALUE neighbors) {=0A        const VALU=
E *base =3D RARRAY_PTR(neighbors);=0A        std::vector<VALUE> sorted_neig=
hbors(base, base + RARRAY_LEN(neighbors));=0A=0A        std::sort(sorted_ne=
ighbors.begin(), sorted_neighbors.end(), boost::bind(&distance, point, _1, =
_2));=0A=0A        return rb_ary_new4(RARRAY_LEN(neighbors), &sorted_neighb=
ors.front());=0A      }=0A    '=0A  end=0Aend=0A=0A# initialize our points=
=0Apoints =3D []=0AN.times {=0A  points << Point.new(rand, rand)=0A}=0A=0An=
earest_neighbors =3D []=0Astart =3D Time.now=0Apoints.each_index { |i|=0A  =
nearest_neighbors[i] =3D find_nearest_neighbors(points[i], points[0...i] + =
points[i+1..(N-1)])=0A}=0Afinish =3D Time.now=0Aputs "Ruby Time: #{finish-s=
tart}"=0A=0Anearest_neighbors_inline =3D []=0Ann =3D NearestNeighbor.new()=
=0Astart =3D Time.now=0Apoints.each_index { |i|=0A  nearest_neighbors_inlin=
e[i] =3D nn.find_nearest_neighbors(points[i], points[0...i] + points[i+1..(=
N-1)])=0A}=0Afinish =3D Time.now=0Aputs "Inline Time: #{finish-start}"=0A
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