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From: willis@cs.athabascau.ca (Tony Willis)
Newsgroups: comp.sys.sgi,comp.lang.fortran
Subject: SGI comments?
Keywords: SGI info, FORTRAN
Message-ID: <958@vax.cs.athabascau.ca>
Date: 2 Mar 91 03:41:01 GMT
Organization: Athabasca University
Lines: 40

My organization is considering the purchase of a SGI 340/380
combo for heavy duty number cruching? We're pretty pleased with
what we've seen and heard so far but I have one nagging
doubt. Most of our heavy-duty applications are parallelizable
to a large degree (at least conceptually!) and the benchmarks
run for us by SGI show that we can indeed get really great
throughput in the compute intensive parts of our programs.
However, I note that the FORTRAN compiler itself will not
handle parallel I/O. This means that when we have 4 or 5 users
read/writing big 1024 x 1024 real*4 images to/from disk
the 380 essentially operates in a linear mode, i.e. if one
job takes 2 minutes, 4 jobs running simultaneously take
about 8 or more minutes.

Now the local SGI sales rep did send me a copy of the latest
SGI FORTRAN manual. I noted in the RELEASE notes that it
said that the SGI C compiler could to I/O in parallel and
that FORTRAN users could do this by making calls to a
C subroutine. So my question is is this really possible?

Most of my FORTRAN I/O comes from reading/writing
direct access files more or less like

	DO 300 I = 1, 1024
		WRITE(UNIT=12,REC=I)(DATA(J,I),J=1,1024)
300	CONTINUE

Could I replace this sort of thing by calls to C and
speed up the I/O, particularly in multi-user mode? (Come on
you SGI guys in Mountain View - help make a sale!!)

Also I'd be interested in any general comments from SGI users
about their satisfaction or otherwise with SGI products?

Please e-mail to me directly at

twillis@drao.nrc.ca

Thanks,
Tony Willis