[Python-Dev] Re: SET_LINENO killer

[Guido van Rossum]

> > But here's some sad news.  I only see a speed increase of 0.5%!  I
> > believe that when we first looked at this patch the speedup was about
> > 5%...  Worse, Tim claims that on his Windows box it's actually 5%
> > slower.  What happened?
> 
> Beats me.  I still see a healthy speed up:
> 
> Before:
> 
> $ ./python ../Lib/test/pystone.py 
> Pystone(1.1) time for 50000 passes = 3.99
> This machine benchmarks at 12531.3 pystones/second
> 
> After:
> 
> $ ./python ../Lib/test/pystone.py 
> Pystone(1.1) time for 50000 passes = 3.65
> This machine benchmarks at 13698.6 pystones/second
> 
> (which is nosing on for 10% faster, actually).
> 
> You're not testing a debug vs a release build or anything like that
> are you?

Absolutely not.  I did a "cvs update -D yesterday" and built a
Python binary.  That was only about 1.5% slower than today's binary
built in the same directory minutes earlier.

On the other hand, on a different machine, I had a checkout that was
approximately 2 days old, and there the latest checkout was about 6%
faster (all without -O).  Perhaps something else has happened in the
last two days that actually is responsible for the speedup?

I'm also happy to report that with current cvs, -O makes almost no
difference: it's only 0.18% faster.  Current cvs witout -O is about
the same speed as two days ago with -O.

So it's still a mystery.  What happened yesterday that could have
caused a speedup?

--Guido van Rossum (home page: http://www.python.org/~guido/)