Re: very different compilation times [no optimisation]

[Basile STARYNKEVITCH <basile at starynkevitch dot net>]

Basile STARYNKEVITCH wrote:
> Ian Lance Taylor wrote:
> > Basile STARYNKEVITCH <basile@starynkevitch.net> writes:
> >
> > > Notice that gcc 4.4 is running four times slower that gcc-4.3!
> >
> > Use the -ftime-report option with both compilers to see where the time
> > is going.
>
> I also put the figures in the PR41971

Strangely, the timing varies widely from one run to another with the same compiler.
glinka ~/tmp 16:41 % time gcc-4.4  -O0 -g -fPIC warmelt-normal-1.i -c -o warmelt-normal-1-gcc-4.4.o
gcc-4.4 -O0 -g -fPIC warmelt-normal-1.i -c -o warmelt-normal-1-gcc-4.4.o  32.44s user 1.75s system 99% cpu 34.472 total
glinka ~/tmp 16:56 % time gcc-4.4  -O0 -g -fPIC warmelt-normal-1.i -c -o warmelt-normal-1-gcc-4.4.o
gcc-4.4 -O0 -g -fPIC warmelt-normal-1.i -c -o warmelt-normal-1-gcc-4.4.o  14.43s user 0.64s system 99% cpu 15.125 total
glinka ~/tmp 16:56 % time gcc-4.4  -O0 -g -fPIC warmelt-normal-1.i -c -o warmelt-normal-1-gcc-4.4.o
gcc-4.4 -O0 -g -fPIC warmelt-normal-1.i -c -o warmelt-normal-1-gcc-4.4.o  39.23s user 1.95s system 99% cpu 41.298 total
glinka ~/tmp 16:57 % time gcc-4.4  -O0 -g -fPIC warmelt-normal-1.i -c -o warmelt-normal-1-gcc-4.4.o
gcc-4.4 -O0 -g -fPIC warmelt-normal-1.i -c -o warmelt-normal-1-gcc-4.4.o  8.69s user 0.32s system 99% cpu 9.046 total
glinka ~/tmp 16:57 % time gcc-4.4  -O0 -g -fPIC warmelt-normal-1.i -c -o warmelt-normal-1-gcc-4.4.o
gcc-4.4 -O0 -g -fPIC warmelt-normal-1.i -c -o warmelt-normal-1-gcc-4.4.o  20.98s user 1.18s system 99% cpu 22.282 total



glinka ~/tmp 16:58 % time gcc-4.3  -O0 -g -fPIC warmelt-normal-1.i -c -o warmelt-normal-1-gcc-4.3.o
gcc-4.3 -O0 -g -fPIC warmelt-normal-1.i -c -o warmelt-normal-1-gcc-4.3.o  44.04s user 2.14s system 99% cpu 46.563 total
glinka ~/tmp 16:59 % time gcc-4.3  -O0 -g -fPIC warmelt-normal-1.i -c -o warmelt-normal-1-gcc-4.3.o
gcc-4.3 -O0 -g -fPIC warmelt-normal-1.i -c -o warmelt-normal-1-gcc-4.3.o  7.12s user 0.27s system 99% cpu 7.402 total
glinka ~/tmp 17:00 % time gcc-4.3  -O0 -g -fPIC warmelt-normal-1.i -c -o warmelt-normal-1-gcc-4.3.o
gcc-4.3 -O0 -g -fPIC warmelt-normal-1.i -c -o warmelt-normal-1-gcc-4.3.o  75.16s user 3.32s system 99% cpu 1:18.97 total
glinka ~/tmp 17:01 % time gcc-4.3  -O0 -g -fPIC warmelt-normal-1.i -c -o warmelt-normal-1-gcc-4.3.o
gcc-4.3 -O0 -g -fPIC warmelt-normal-1.i -c -o warmelt-normal-1-gcc-4.3.o  20.78s user 0.96s system 99% cpu 21.856 total
glinka ~/tmp 17:01 % time gcc-4.3  -O0 -g -fPIC warmelt-normal-1.i -c -o warmelt-normal-1-gcc-4.3.o
gcc-4.3 -O0 -g -fPIC warmelt-normal-1.i -c -o warmelt-normal-1-gcc-4.3.o  7.11s user 0.32s system 99% cpu 7.442 total

I have no idea of what is happenning. (Maybe randomized address & malloc???) My desktop is not loaded (and is quadricore).


Regards.


--
Basile STARYNKEVITCH         http://starynkevitch.net/Basile/
email: basile<at>starynkevitch<dot>net mobile: +33 6 8501 2359
8, rue de la Faiencerie, 92340 Bourg La Reine, France
*** opinions {are only mines, sont seulement les miennes} ***