Python and STL efficiency

[Mc Osten]

Tim N. van der Leeuw <tim.leeuwvander at nl.unisys.com> wrote:


> But your C++ program outputs times in seconds, right? So all
> compilations except for the first two give results in less than a
> second, right? (meaning the optimizations of your standard-compilation
> give worst results than -O3?)

Yes. It's in seconds but the benchmark that are one order of magnitudo
less than the others have of a different "size" (100000 instead of
1000000).  That is cut and paste from my terminal... I think it's a
mess. I do it all again from scratch.

> BTW, I don't quite understand your gcc optimizations for the first 2
> compiles anyways: two -O options with different values. Doesn't that
> mean the 2nd -O takes preference, and the compilation is at -O2 instead
> of -O3?
> Why both -O3 and -O2 at the command-line?

I forgot I put -O2 in my $FAST_FLAGS. I don't know what I was thinking
about.

This the correct version

$ g++ -Os -pipe -march=pentium-m -msse3 -fomit-frame-pointer
-mfpmath=sse  -o set_impl set_impl.cpp 

$ ./set_impl 
What do you know?
chicken crosses road
fool
so long...
What do you know?
chicken crosses road
fool
so long...
Elapsed 6.3
Elapsed 2.1

$ g++ -O2 -pipe -march=pentium-m -msse3 -fomit-frame-pointer
-mfpmath=sse  -o set_impl set_impl.cpp 
$ ./set_impl 
What do you know?
chicken crosses road
fool
so long...
What do you know?
chicken crosses road
fool
so long...
Elapsed 5.8
Elapsed 1.7

$ g++ -O3 -pipe -march=pentium-m -msse3 -fomit-frame-pointer
-mfpmath=sse  -o set_impl set_impl.cpp 
$ ./set_impl  
What do you know?
chicken crosses road
fool
so long...
What do you know?
chicken crosses road
fool
so long...
Elapsed 5.79
Elapsed 1.72

$ g++ -pipe -march=pentium-m -msse3 -fomit-frame-pointer -mfpmath=sse
-o set_impl set_impl.cpp 
$ ./set_impl
What do you know?
chicken crosses road
fool
so long...
What do you know?
chicken crosses road
fool
so long...
Elapsed 7.12
Elapsed 2.98

$ python -O set_impl.py 
so long...
What do you know
fool
chicken crosses road
so long...
What do you know
fool
chicken crosses road
Elapsed: 1.370000 seconds
Elapsed: 3.800000 seconds

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