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Re: Coarray article for the upcoming GCC Summit.
- From: Tobias Burnus <burnus at net-b dot de>
- To: longb at cray dot com
- Cc: MOENE Toon <toon dot moene at cnrm dot meteo dot fr>, fortran at gcc dot gnu dot org, j dot k dot reid at rl dot ac dot uk, dannagle at verizon dot net
- Date: Mon, 21 Apr 2008 21:11:59 +0200
- Subject: Re: Coarray article for the upcoming GCC Summit.
- References: <4809C31C.9080502@cnrm.meteo.fr> <480CC606.8090603@cray.com>
Bill Long wrote:
8) In section 7 on implementation, I would probably lean towards the
general implementation in terms of GASNet rather than MPI. GASNet is
generally a shorter path to the hardware, and hence more efficient.
Perhaps more important, the GNU version of UPC is done with GASNet (at
least that's my impression), and reusing work already done within the
GNU umbrella seems like a good idea. In fact, pointing out that much
of the work done for UPC can be reused for Fortran is probably a good
selling point.
I was also wondering the other day whether UPC could help (see GCC's
bugzilla PR18918). However, I have the impression that since 2006
nothing has happend and UPC is not part of the GCC itself. I actually do
not know whether they have signed a copyright assignment with the FSF.
If not, we cannot take anything from UPC.
At least the GCC UPC I found was based on GCC 4.0.x which is already
slightly outdated:
http://www.intrepid.com/upc.html
Regarding GASNet (http://gasnet.cs.berkeley.edu/), this would be indeed
an alternative (as I wrote in PR18918). The advantage of MPI is that is
ubiquitous. However, GASNet seems to be faster and seems to support also
MPI as network backend (as TCP/IP, infiniband, myrinet, ....). [By the
way, GASNet is under a BSD-like licence.]
Has anyone experience with GCC UPC or knows their licence status
(agreement with FSF yes/no) or whether they indent to get it merged with
standard GCC?
I think that having coarrays available in gfortran would be a
tremendous plus for the Fortran user community.
So do I, although I would expect that it takes quite a while until
coarrays are wider used. (At least the Fortran programmers I know strive
for large compiler compatibility (Fortran 95 without allocatable TR,
maybe even without some new F95 features). Though with conditional
compiling some Fortran 2003 features are creeping in.)
Tobias