[Python-Dev] Re: SET_LINENO killer

Christian Tismer tismer@tismer.com
Thu, 15 Aug 2002 19:43:20 +0200

Guido van Rossum wrote:

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

Without looking ijto it, but I have spent weeks in
speeding up the main loop, and I can tell you that
it shows some fractal behavior, at least under
Windows. It appears to make a difference, when small
code moves happen, or some variable vanishes and the
compiler decides to re-arrange registers or change
code ordering, and especially folding. I experienced
that some changes of mine caused the compiler to
re-use a common code sequence, which caused one
more jump and made it slower.

Just to tell you, it isn't always under your control,
and something that *should* run faster is actually
slower, especially when you're fiddling with
fractions of percentiles.

SET_LINENO was so cheap, that after some tests,
I decided to keep it in, also since I found it
useful for line-wise interrupts.

Btw., with the new patch, how is tracing done now?
(sorry, I could read the sources but I'm under pressure)

cheers - chris

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