[Python-Dev] Reworking the GIL

Collin Winter collinw at gmail.com
Mon Oct 26 22:50:14 CET 2009

On Mon, Oct 26, 2009 at 2:43 PM, Antoine Pitrou <solipsis at pitrou.net> wrote:
> Collin Winter <collinw <at> gmail.com> writes:
> [the Dave Beazley benchmark]
>> The results below are benchmarking py3k as the control, newgil as the
>> experiment. When it says "x% faster", that is a measure of newgil's
>> performance over py3k's.
>> With two threads:
>> iterative_count:
>> Min: 0.336573 -> 0.387782: 13.21% slower  # I've run this
>> configuration multiple times and gotten the same slowdown.
>> Avg: 0.338473 -> 0.418559: 19.13% slower
> Those numbers are not very in line with the other "iterative_count" results.
> Since iterative_count just runs the loop N times in a row, results should be
> proportional to the number N ("number of threads").
> Besides, there's no reason for single-threaded performance to be degraded since
> the fast path of the eval loop actually got a bit streamlined (there is no
> volatile ticker to decrement).

I agree those numbers are out of line with the others and make no
sense. I've run it with two threads several times and the results are
consistent on this machine. I'm digging into it a bit more.


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