[issue12175] FileIO.readall() read the file position and size at each read

[STINNER Victor]

STINNER Victor <victor.stinner at haypocalc.com> added the comment:

Number of syscalls without the patch -> with the patch:

- read the README file, text mode: 17 -> 12 syscalls (-5)
- read the README file, binary mode: 15 -> 11 syscalls (-4)
- read a binary file of 10 MB: 17 -> 12 syscalls (-5)

Quick benchmark open('README').read(); open('README', 'rb').read() in a loop: 359.1 ms -> 335.4 ms (-7%). So it's not really faster.

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue12175>
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