Xref: utzoo comp.lang.fortran:1599 comp.lang.misc:2305
Path: utzoo!utgpu!watmath!clyde!att!rutgers!tut.cis.ohio-state.edu!bloom-beacon!gatech!gitpyr!loligo!mccalpin
From: mccalpin@loligo.fsu.edu (John McCalpin)
Newsgroups: comp.lang.fortran,comp.lang.misc,comp.sys.super
Subject: Re: Assembly or ....
Keywords: Assembler, HLL
Message-ID: <159@loligo.fsu.edu>
Date: 1 Dec 88 23:12:51 GMT
Reply-To: mccalpin@loligo.UUCP (John McCalpin)
Organization: Supercomputer Computations Research Institute
Lines: 18
References:

I notice that no one has discussed supercomputers in this long 
discussion on the merits of learning assembly language.  To achieve
any sort of reasonable performance on a vector supercomputer, you
must know a lot about the architecture.  Some machines are worse
than others --- the CDC/ETA machines and the Cray-2 come to mind as
machines on which it is remarkably easy to get bad performance....

On the other hand, it is almost never necessary for users to _write_
is assembly language on these machines to get good performance - you
just need to know what the vectorizer is able to convert into 
efficient code.  Also on the CDC/ETA machines, the entire instruction
set is available in FTN200 anyway via special calls. (This actually
produces inline code, but they are written as subroutine calls).

John D. McCalpin
Supercomputer Computations Research Institute
The Florida State University
mccalpin@masig1.ocean.fsu.edu