Re: gfortran 4.3.2 about 3x slower than g77 for scientific application

[Julian King <jking dot phys at gmail dot com>]

-march=native makes negligible difference to the running time.

I agree with you about the profiling being weird in terms of the
number of calls. This is to the same data though, and the outputs of
the program are the same. I just wonder if gprof is not catching all
the calls somehow?

-Wall produces a large number of warnings, but all of them relate to
1) nonconforming tab characteres
2) unused dummy variables
3) unused variables.

There are no other warnings of note..

Julian

On Wed, May 13, 2009 at 9:24 PM, Steve Kargl
<sgk@troutmask.apl.washington.edu> wrote:
>
> On Wed, May 13, 2009 at 11:50:13AM -0700, VelocideX wrote:
> >
> > (i.e. it is computationally intensive).
> >
> > I am on a Intel Core 2 Duo P8700 processor with 4 GB RAM, running OpenSuSE
> > 11.1 64 bit (i.e x86-64 architecture).
> >
> > Executing the program on identical data is about 3x slower in gfortran than
> > g77 (v3.3.3-hammer). This seems a serious deficiency given that all the run
> > time in the program is spent in relatively simple calls. Both versions were
> > compiled with the flag -O2 only.
>
> Try adding -march=native to the gfortran command line.
>
> > Here are the gprof results for the g77:
> > ? % ? cumulative ? self ? ? ? ? ? ? ?self ? ? total
> > ?time ? seconds ? seconds ? ?calls ? s/call ? s/call ?name
> > ?64.12 ? ? ?2.52 ? ? 2.52 ? ?23679 ? ? 0.00 ? ? 0.00 ?vp_spvoigte__
> > ?19.34 ? ? ?3.28 ? ? 0.76 28574044 ? ? 0.00 ? ? 0.00 ?voigt_
> > ? 6.36 ? ? ?3.53 ? ? 0.25 ? ? ? 12 ? ? 0.02 ? ? 0.28 ?deriv_
> > ? 4.33 ? ? ?3.70 ? ? 0.17 32747695 ? ? 0.00 ? ? 0.00 ?dexpf_
> > ? 3.05 ? ? ?3.82 ? ? 0.12 ? ? ?877 ? ? 0.00 ? ? 0.00 ?vp_chspread__
> > ? 1.27 ? ? ?3.87 ? ? 0.05 ? ? ? ?1 ? ? 0.05 ? ? 0.05 ?pr_sort__
> > ? 0.51 ? ? ?3.89 ? ? 0.02 ? ? ? ?1 ? ? 0.02 ? ? 0.02 ?probks_
> > ? 0.25 ? ? ?3.90 ? ? 0.01 ? ?23679 ? ? 0.00 ? ? 0.00 ?calcn_
> > ? 0.25 ? ? ?3.91 ? ? 0.01 ? ? ?877 ? ? 0.00 ? ? 0.00 ?vp_chipconv__
> > ? 0.25 ? ? ?3.92 ? ? 0.01 ? ? ? 11 ? ? 0.00 ? ? 0.00 ?udchole_
> > ? 0.25 ? ? ?3.93 ? ? 0.01 ? ? ? ?1 ? ? 0.01 ? ? 0.01 ?pldef_
> > ? 0.00 ? ? ?3.93 ? ? 0.00 ? 550174 ? ? 0.00 ? ? 0.00 ?ucase_
> >
> > ...and for the gfortran (slower version) execution:
> > ? % ? cumulative ? self ? ? ? ? ? ? ?self ? ? total
> > ?time ? seconds ? seconds ? ?calls ? s/call ? s/call ?name
> > ?43.27 ? ? ?3.28 ? ? 3.28 ? ?33885 ? ? 0.00 ? ? 0.00 ?vp_spvoigte_
> > ?27.04 ? ? ?5.33 ? ? 2.05 ? ? 1255 ? ? 0.00 ? ? 0.00 ?vp_subchspread_
> > ?16.36 ? ? ?6.57 ? ? 1.24 41100608 ? ? 0.00 ? ? 0.00 ?voigt_
> > ? 6.99 ? ? ?7.10 ? ? 0.53 528972139 ? ? 0.00 ? ? 0.00 ?dexpf_
> > ? 3.56 ? ? ?7.37 ? ? 0.27 ? ? ? 17 ? ? 0.02 ? ? 0.38 ?deriv_
> > ? 0.66 ? ? ?7.42 ? ? 0.05 ? ? ? ?1 ? ? 0.05 ? ? 0.05 ?pr_sort_
> > ? 0.66 ? ? ?7.47 ? ? 0.05 ? ? ? ?1 ? ? 0.05 ? ? 0.05 ?probks_
> > ? 0.40 ? ? ?7.50 ? ? 0.03 ? 478767 ? ? 0.00 ? ? 0.00 ?varythis_
> > ? 0.40 ? ? ?7.53 ? ? 0.03 ? ? ? ?1 ? ? 0.03 ? ? 7.52 ?vp_ucoptv_
> > ? 0.26 ? ? ?7.55 ? ? 0.02 ? ?33878 ? ? 0.00 ? ? 0.00 ?vp_archwav_
> > ? 0.13 ? ? ?7.56 ? ? 0.01 ? ?33885 ? ? 0.00 ? ? 0.00 ?calcn_
> > ? 0.13 ? ? ?7.57 ? ? 0.01 ? ? 1255 ? ? 0.00 ? ? 0.00 ?vp_chipconv_
> > ? 0.13 ? ? ?7.58 ? ? 0.01 ? ? ? ?1 ? ? 0.01 ? ? 0.01 ?vp_gwclinfits_
> > ? 0.00 ? ? ?7.58 ? ? 0.00 ? 793778 ? ? 0.00 ? ? 0.00 ?ucase_
> >
>
> Are you using the same input for this comparison because the
> number of calls to various functions suggest that you are
> taking drastically different code paths (eg, see # of
> calls for dexpf and voigt)?.
>
> If you add -Wall to the gfortran command line, do you get
> a large number of warnings?
>
> --
> Steve