[Bug libfortran/21820] Really, really, horrible IO performance

["jblomqvi at cc dot hut dot fi" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #15 from jblomqvi at cc dot hut dot fi  2005-11-01 22:09 -------
(In reply to comment #14)
> (In reply to comment #13)
> > The patch from #12 has been committed to mainline.
> 
> So should this bug be closed?
> 

It depends on what you consider "really, really horrible IO performance". ;-)
Getting rid of mmap (the patch referred to above) improved performance by a
factor of 25, and I think before I made those measurements there were some
patches committed which made the mmap window bigger or somesuch, improving
performance compared to the situation when the bug was filed. So IMHO we have
made huge improvements.

OTOH we still lose to ifort by a factor of 6 or so. The major reason is that
ifort does bulk transfers for implied do loops, while gfortran doesn't.
Changing the code to use array transfers makes gfortran only about a factor of
1.5 slower than ifort.

Personally, I think we can keep the bug around for reference, but change the
priority to "enhancement". 


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21820