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List:       pypy-dev
Subject:    Re: [pypy-dev] PyPy is much slower than CPython example / question
From:       Romain Guillebert <romain.py () gmail ! com>
Date:       2011-07-08 0:30:48
Message-ID: 20110708003048.GA8477 () ubuntu
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Hi

When I change this line:

primes[i*i:N+1:i] = repeat(False, len(primes[i*i:N+1:i]))

into this :

primes[i*i:N+1:i] = [False] * len(primes[i*i:N+1:i])

PyPy is much faster (but is still slower than CPython), so I would guess
that the repeat function is the one to blame.

Cheers
Romain

On Fri, Jul 08, 2011 at 02:03:20AM +0300, Alexander Petrov wrote:
> Hi.
> 
> I'm new to PyPy and was trying to run some tests to see orders of
> speed improvement.
> 
> Short script generating list of prime numbers using rather
> straightforward implementation of Eratosthene's sieve.
> Script: http://paste.pocoo.org/show/432727/
> 
> Typical results: http://paste.pocoo.org/show/432733/
> (I thought that is due to absense of SSE2 on first computer, but I've
> rechecked on Intel(R) Xeon(R) CPU L5520 @ 2.27GHz with similar
> results).
> 
> I'm getting that CPython is nearly 4-8 times faster than PyPy.
> Is it a bug in PyPy or what is wrong (may be "specific" to PyPy) in my script?
> 
> Alex.
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