On 7 Feb 2010, at 05:27, exarkun@twistedmatrix.com wrote:
Do you know of a case where it's actually slow? If not, how convincing should this argument really be? Perhaps we can measure it on a few platforms before passing judgement.
On Mac OS X at least, system calls are notoriously slow. I think it has to do with Mach overhead, or something… $ arch -arch ppc /usr/bin/python2.6 -m timeit -s 'def f(): pass' 'f()' 1000000 loops, best of 3: 0.476 usec per loop $ arch -arch ppc /usr/bin/python2.6 -m timeit -s 'from os import getcwd' 'getcwd()' 10000 loops, best of 3: 21.9 usec per loop $ arch -arch i386 /usr/bin/python2.6 -m timeit -s 'def f(): pass' 'f()' 1000000 loops, best of 3: 0.234 usec per loop $ arch -arch i386 /usr/bin/python2.6 -m timeit -s 'from os import getcwd' 'getcwd()' 100000 loops, best of 3: 14.1 usec per loop $ arch -arch x86_64 /usr/bin/python2.6 -m timeit -s 'def f(): pass' 'f()' 10000000 loops, best of 3: 0.182 usec per loop $ arch -arch x86_64 /usr/bin/python2.6 -m timeit -s 'from os import getcwd' 'getcwd()' 100000 loops, best of 3: 11 usec per loop For maximum reproducibility, I used the stock Python 2.6.1 included in Mac OS X 10.6.2. In other words ‘os.getcwd()’ is more than fifty times as slow as a regular function call when using Mac OS X. -- Dan Villiom Podlaski Christiansen danchr@gmail.com