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

["Tobias dot Schlueter at physik dot uni-muenchen dot de" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #16 from Tobias dot Schlueter at physik dot uni-muenchen dot de  2005-11-01 22:31 -------
Subject: Re:  Really, really, horrible IO performance

jblomqvi at cc dot hut dot fi wrote:
> 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". 

We could probably close this as a duplicate of PR16339.


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