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[Python-Dev] file.readinto performance regression in Python 3.2 vs. 2.7?

Antoine Pitrou solipsis at pitrou.net
Fri Nov 25 01:23:19 CET 2011 
On Thu, 24 Nov 2011 20:53:30 +0200
Eli Bendersky <eliben at gmail.com> wrote:
> 
> Sure. Updated the default branch just now and built:
> 
> $1 -m timeit -s'import fileread_bytearray' 'fileread_bytearray.justread()'
> 1000 loops, best of 3: 1.14 msec per loop
> $1 -m timeit -s'import fileread_bytearray'
> 'fileread_bytearray.readandcopy()'
> 100 loops, best of 3: 2.78 msec per loop
> $1 -m timeit -s'import fileread_bytearray' 'fileread_bytearray.readinto()'
> 1000 loops, best of 3: 1.6 msec per loop
> 
> Strange. Although here, like in python 2, the performance of readinto is
> close to justread and much faster than readandcopy, but justread itself is
> much slower than in 2.7 and 3.2!

This seems to be a side-effect of
http://hg.python.org/cpython/rev/f8a697bc3ca8/

Now I'm not sure if these numbers matter a lot.  1.6ms for a 3.6MB file
is still more than 2 GB/s.

Regards

Antoine.
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