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From: cdl@chiton.ucsd.edu (Carl Lowenstein)
Newsgroups: comp.unix.questions
Subject: Re: System turns into pig after 66040 installation on HP-UX
Message-ID: <1060@chiton.ucsd.edu>
Date: 9 May 91 15:55:16 GMT
References: <26810@adm.brl.mil>
Reply-To: cdl@chiton (Carl Lowenstein)
Organization: Marine Physical Laboratory, UCSD
Lines: 25

In article <26810@adm.brl.mil> FLYNN%EVALUN11.BITNET@cunyvm.cuny.edu (Mark F. Flynn) writes:
>We're running HP-UX 7.05 on an Apollo 400t, and have just installed the
>new and wonderful 68040 processor. What we have noticed is that certain
>jobs spend from 50% to 90% of their time doing system calls, as opposed
>to user time.
>So far, we have only seen it on Fortran code
>The HP people here havn't a clue.

Looks to me like you have run into the 68040 floating-point problem, just
like us people with NeXT computers did a few months ago.

The 68040 does not have the full panoply of floating-point instructions
that the 68882 floating-point unit does.  (e.g. no transcendentals)
Thus many of the FP instructions in your Fortran code have become
"unimplemented instructions" and trap to the operating system, where
they have to be suitably interpreted and dispatched.

The long-term solution is to recompile the programs and link them with
an appropriate math library that does not use the 68882 instructions which
are not present in the 68040.

-- 
        carl lowenstein         marine physical lab     u.c. san diego
        {decvax|ucbvax} !ucsd!mpl!cdl                 cdl@mpl.ucsd.edu
                                                  clowenstein@ucsd.edu