Steve Holden schrieb: > Ben North wrote: > [...] >> Guido van Rossum wrote: >>> I missed discussion of the source of the 1%. Does it slow down pystone >>> or other benchmarks by 1%? That would be really odd, since I can't >>> imagine that the code path changes in any way for code that doesn't >>> use the feature. Is it that the ceval main loop slows down by having >>> two more cases? >> >> That seems to be it, yes. I tested this by leaving the grammar, >> compilation, and AST changes in, and conditionally compiling just the >> three extra cases in the ceval main loop. Measurements were noisy >> though, as Josiah Carlson has also experienced: >> >>> I've found variations of up to 3% in benchark times that seemed to be >>> based on whether I was drinking juice or eating a scone while working. >> >> I'm afraid I can't remember what I was eating or drinking at the time I >> did my tests. >> > A further data point is that modern machines seem to give timing > variabilities due to CPU temperature variations even if you always eat > exactly the same thing. > > One of the interesting facts to emerge from the Need for Speed sprint > last year is that architectural complexities at many levels make it > extremely difficult nowadays to build a repeatable benchmark of any kind.
My personal experience using a dual core machine (on WinXP) is that timing results become much more reproducible. Thomas _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
