Path: utzoo!attcan!uunet!cs.utexas.edu!tut.cis.ohio-state.edu!ucbvax!UOGUELPH.BITNET!LEONARDZ
From: LEONARDZ@UOGUELPH.BITNET ("Len Zaifman  UoGuelph 824-4120 xt 6566", 519)
Newsgroups: comp.sys.sgi
Subject: FORTRAN program optimisation
Message-ID: <89Aug25.093608edt.57688@ugw.utcs.utoronto.ca>
Date: 25 Aug 89 13:33:30 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 33


     I need help on two issues.

     1 . I am trying to compile some fortran code with optimisation. At O2 ,
        several routines ( this program has several hundred  ) hit the error
       not optimised beacuase global tables are not large enough, use
        Olimit > nnn where nnn is some number larger than 500. The question
        is , does it hurt the performance of the program , or the program
        size to compile  with Olimit nnn,where nnn is greater than the largest
        reported size required, for all the routines , whether they need the
        space or not ?? The program is large enough as it is , and I am trying
        to enhance its runtime execution speed as much as possible.
             To that end I would also like someone from SGI to comment on the
        advisability of using O3. I was told that at the moment this level of
        optimisation is unsafe. Is that true , and what performance enhancement
        is expected over O2 optimisation ?? Also, for a very large program such
        as this what are the recommended analysis tools on IRIX to help
        optimise the performance(hopefully without source code changes ). I am
        looking for tools which help restructure the binary(loaded) code to
        enhance performance.

       2. On the user interface side , I see a need for easier command recall
          than using !nnn to recall a command. Recently I worked on an Apollo
          where command recall and editting was available through mouse
          highlighting, cutting and pasting (ie like a mac). Can this be done
          in IRIX now (3.1 x level)? will it be available at 3.2 ?? In
          Workspace ??

                Thanks


                                                          Regards,
                                                          Len Zaifman