Python IS slow ! [was] Re: Python too slow for real world

[Christian Tismer]

Just a word about LOAD_FAST and LOAD_CONST.

I looked into the macro expansions in ceval.c, and the real
difference is just that LOAD_FAST has a shortcut in the
interpreter loop which reads

			if (x != NULL) continue;

LOAD_CONST doesn't have this. I did a quick test to see
the difference, and afterwards, LOAD_CONST was in fact
slightly faster than LOAD_FAST.
But...

result = """
>>> test()
func1 (6.32, 42)  # LOAD_FAST
func2 (7.36, 42)  # LOAD_GLOBAL
func2 (6.21, 42)  # should read func3, does LOAD_CONST
>>> 
# with patch to ceval.c
>>> test()
func1 (7.08, 42)
func2 (7.8, 42)
func2 (6.76, 42)
>>> 
"""

... due to the platform specific optimization strategy
of the compiler, an overall speed loss was the effect.
Makes no sense to supply a patch. Instead I would claim
that both opcodes are virtually at the same speed and
one should not worry about it.

ciao - chris   (back to real work:)

-- 
Christian Tismer             :^)   <mailto:tismer at appliedbiometrics.com>
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