PyPy 1.4: Ouroboros in practice

Re:PyPy 1.4: Ouroboros in practice by d0mine on Saturday November 27, 2010 @10:28AM (#1945103)

There is something strange with the example.

  $ pypy -mtimeit -s'import math; sin=math.sin' \
      '[x*x+sin(x/1e6) for x in xrange(1000000)]'
  10 loops, best of 3: 156 msec per loop

With no division it is slower (?):

  $ pypy -mtimeit -s'import math; sin=math.sin' \
       '[x*x+sin(x) for x in xrange(1000000)]'
  10 loops, best of 3: 188 msec per loop

CPython shows expected behavior:

  $ python2.7 -mtimeit -s'import math; sin=math.sin' \
    '[x*x+sin(x) for x in xrange(1000000)]'
  10 loops, best of 3: 231 msec per loop

  $ python2.7 -mtimeit -s'import math; sin=math.sin' \
    '[x*x+sin(x/1e6) for x in xrange(1000000)]'
  10 loops, best of 3: 253 msec per loop

CPython is faster for tiny cases:

  $ pypy -mtimeit '[x*x for x in xrange(1000000)]'
  10 loops, best of 3: 126 msec per loop

  $ python2.7 -mtimeit '[x*x for x in xrange(1000000)]'
  10 loops, best of 3: 67.3 msec per loop

  $ pypy -mtimeit '[x*x*x for x in xrange(1000000)]'
  10 loops, best of 3: 123 msec per loop

  $ python2.7 -mtimeit '[x*x*x for x in xrange(1000000)]'
  10 loops, best of 3: 118 msec per loop

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Re:PyPy 1.4: Ouroboros in practice by orangecat on Saturday November 27, 2010 @09:02PM (#1946423)

With no division it is slower (?)

Very interesting. Looks like sin is faster for arguments less than pi/4 (~=0.7853981633974483):

Edit: "Intel's sin/cos implementation sucks golfballs through gardenhoses for arguments outside of [-pi/4,pi/4]": http://stackoverflow.com/questions/523531/fast-transcendent-...

    $ pypy -mtimeit -s'import math; sin=math.sin; a=0.786' '[sin(a) for x in xrange(1000000)]'
    10 loops, best of 3: 395 msec per loop

    $ pypy -mtimeit -s'import math; sin=math.sin; a=0.785' '[sin(a) for x in xrange(1000000)]'
    10 loops, best of 3: 375 msec per loop

    $ python -mtimeit -s'import math; sin=math.sin; a=0.786' '[sin(a) for x in xrange(1000000)]'
    10 loops, best of 3: 177 msec per loop

    $ python -mtimeit -s'import math; sin=math.sin; a=0.785' '[sin(a) for x in xrange(1000000)]'
    10 loops, best of 3: 155 msec per loop

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