[MITgcm-support] bluesky build

[Constantinos Evangelinos]

On Tuesday 07 June 2005 13:43, Ed Hill wrote:

> On Tue, 2005-06-07 at 11:25 -0400, Mike Spall wrote:
> > Hi All,
> >
> > I have tried compiling MITgcm on ncar's bluesky.  It seems
> > to be working in that I get no errors, but it also seems
> > to be taking a very long time.  I compiled with
> > MITgcm/tools/build_options/sp4+mpi yesterday and
> > it was not done after > 20 minutes so I killed it.
> > I was doing this interactively, not by batch.
> > Does this sound right?
>
> Hi Mike,
>
> This is only a guess, but it sounds like the very slow build could be
> due to slow disk I/O.  Please contact the bluesky admins since there is
> almost nothing that we can do about it from our side.

Actually the issue is in the use of "-qhot" which does higher level 
transformations to loops for speed purposes. Unfortunately use of -qhot, or 
-O4/O5 (that add -qipa at different levels) slows down compilation on the IBM 
systems to impossibly long times (several hours long - no kidding). Kill off 
the -qhot option in the Makefile (or ask for -ieee from genmake, which also 
should drastically reduce roundoff error differences introduced by 
optimization) to get more reasonable compilation times.

Constantinos
-- 
Dr. Constantinos Evangelinos
Department of Earth, Atmospheric and Planetary Sciences
Massachusetts Institute of Technology