[pypy-dev] JIT'ed function performance degrades

[Armin Rigo]

Hi Hart,

On Thu, Aug 19, 2010 at 11:04:48PM -0700, Hart's Antler wrote:
> I had seen the blog post before by Carl Friedrich Bolz about JIT'ing
> and that he was able to speed things up 22x faster than plain RPython
> translated to C, so that got me curious about the JIT.

You cannot expect any program to get 22x faster with RPython+JIT than it
is with just RPython.  That would be like saying that any C program can
get 22x faster if we apply some special JIT on it.  For a general C
program, such a statement makes no sense -- no JIT can help.

The PyPy JIT can help *only* if the RPython program in question is some
kind of interpreter, with a loose definition of interpreter.  That's why
we can apply the PyPy JIT to the Python interpreter written in RPython;
or to some other examples, like Carl Friedrich's blog post about the
regular expressions "interpreter".


A bientot,

Armin.