About those workstations....

[fredvc \\at// esvax.dnet.dupont.com]

  RE:	Attack of the killer workstations
 From:   Joe Leonard
         jle \\at// world.std.com
 >>Reviewing the recent discussion regarding C vs. Fortran and structured
 vs.
 >>spagetti coding, isn't it reasonable to consider the time of the
 programmer
 >>as more important that the code's runtime (within reason)?  Given that
 >>approx. $20k workstations are comparable to Cray machines, isn't 10-ish%
 >>overhead more than worth the human time savings through better-thought-
 >>out programming (structured, modular, OO, etc.)?  I hope the day's past
 >>for really needing to count cycles in loops - as one can wait for the
 next
 >>version of workstation xxx to gain appreciable speedups.
 We have found it to be a mistake to depend upon workstation performance
 (MIPS/MFLOPS), per se.  There is a lot that goes into getting good perform-
 ance out of a box besides processor speed.  This becomes painfully clear as
 the problem gets large.  Caching is commonly used in such systems, and this
 can quickly become a performance bottleneck.  What you pay for in getting a
 CRAY is a balanced system in terms of cpu, memory access, and disk access
 speeds.
 >>Obviously, this isn't the case for mpp machines, for which the consensus
 is
 >>that one must rethink and/or reimplement algorithm's in order to use
 >>the hardware to advantage.  Still, this might prove to be an example
 where
 >>clearer coding styles might turn out to be a win after all...
 Good code runs better than bad code on ANY machine.  The "edge" tends
 to be
 bigger on a CRAY, but the edge is still there on a VAX, SUN, IBM 6000, etc.
 We recently optimized a program for the CRAY and found that the optimized
 version ran better on the ALL machines we tested.
 		CRAY speed up: ~63x
 		 VAX speed up: ~17
 	    IBM 6000 speed up: ~20
 Mearly putting the original code on a box with a faster cpu would not give
 this kind of payback.  There was nothing "pathological" about the
 program.
 It just needed some TLC!!
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                            FREDERIC A. VAN-CATLEDGE
 Scientific Computing Division         ||   Office: (302) 695-1187
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