Real-world Python code 700 times slower than C

[Henrik Motakef]

brent.burley at disney.com (Brent Burley) writes:

> What I really want is something spiritually equivalent to a portable
> inline assembly language with python-ish syntax that generates really
> fast native code and seamlessly integrates with python.  I can dream
> can't I?

Sorry, I don't know something like this. However, mind that there are
other languages than Python and C.

For example, I tried how your function performs in OCaml. The code
looks like this:

------

let ramp result size start stop =
  let step = (stop - start) / (size - 1) in
  for i = 0 to size - 1 do
    result.(i) <- start + step * i
  done

let main () =
  let array = Array.make 10000 0 in
  for i = 0 to 100000 do
    ramp array 10000 0 1
  done

let _ = main ()

------

The only difference is that start and stop (end is a reserved word in
OCaml) are integers. OCaml quite strictly separates Integer and Float
arithmetic, and I was to lazy to care... However, I think you get the
idea anyways.

The results of running the differerent versions of ramp on my 600MHz
Duron with 196MB RAM and OpenBSD:

------
#time ./ramp.py
real	0m4.653s
user	0m4.639s
sys	0m0.000s

#time ./ramp_ml_bytecode
real	0m0.243s
user	0m0.234s
sys	0m0.001s

#time ./ramp_c
real	0m9.412s
user	0m9.390s
sys	0m0.008s

#time ./ramp_ml_native 
real	0m12.283s
user	0m12.257s
sys	0m0.008s

#time ./ramp_ml_unsafe 
real	0m10.066s
user	0m10.029s
sys	0m0.008s


-----

ramp.py and ramp_c are taken unchanged from your posting, ramp_c is
compiled with "gcc -o ramp_c -O2 ramp.c". ramp_ml_bytecode is
compiled to platform independent bytecode, and, like ramp.py, iterates
only 100 times. ramp_ml_native and ramp_ml_unsafe do, like ramp_c,
100.000 iterations, and are compiled to native, standalone
machine-code. ramp_ml_unsafe used the -unsafe compiler option, turning
off bounds-checking, so that you can have C-style segfaults even
without C :)

I think OCaml may be an option if execution speed is important, but
you still want to have readable syntax (O.K. - once you get used to
it), garbage collection, and generally most of the things C lacks.
However, I don't know a simple way of interfacing OCaml and Python,
you'll probably stil need some C for glueing them together.

IIRC there once were a project (called Viper?) that tried to implement
a Python interpreter in OCaml, but I don't know how far it got. Does
anybody know more?

Regards
Henrik