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- Xref: sparky comp.arch:10467 comp.lang.misc:3527
- Path: sparky!uunet!snorkelwacker.mit.edu!ai-lab!arolla!tmb
- From: tmb@arollaidiap.ch (Thomas M. Breuel)
- Newsgroups: comp.arch,comp.lang.misc
- Subject: Re: Hardware Support for Numeric Algorithms
- Date: 6 Nov 1992 17:18:12 GMT
- Organization: MIT Artificial Intelligence Lab
- Lines: 50
- Distribution: world
- Message-ID: <1de9ckINNfj7@life.ai.mit.edu>
- References: <BwJ4uz.1rA@rice.edu> <1992Oct23.004313.29196@ntuix.ntu.ac.sg> <1992Oct29.153514.22927@yrloc.ipsa.reuter.COM> <1992Nov5.202412.7266@linus.mitre.org>
- Reply-To: tmb@ai.mit.edu
- NNTP-Posting-Host: arolla.idiap.ch
-
- In article <1992Nov5.202412.7266@linus.mitre.org>, bs@gauss.mitre.org (Robert D. Silverman) writes:
- |> In article <1992Oct29.153514.22927@yrloc.ipsa.reuter.COM> rbe@yrloc.ipsa.reuter.COM (Robert Bernecky) writes:
- |> :
- |> :I write programs for correctness and maintainability first, THEN worry
- |> :about little details such as performance. If you create something that's
- |>
- |> You've probably never done any large scale computing.
- |>
- |> I measure the run time of my algorithms in MIPS-YEARS. A MIPS-YEAR
- |> is a 1 MIPS machine running for 1 year, or approximately 3.1 x 10^13
- |> instructions. Jobs that take several hundred MIPS-YEARS are not uncommon.
- |>
- |> Needless to say, there are people who have to worry about speed FIRST,
- |> and that other considerations are (almost) irrelevent.
- |>
- |> I wish you people would stop insulting Herman simply because his requirements
- |> leads to code that is different from your petty and self-righteous
- |> pre-conceived notions about coding style.
- |>
- |> :wrong, or that has to be scrapped in a year because nobody can understand
- |> :it, who cares how fast it runs?
- |>
- |> Not everyone writes commercial code, or code for customers. Maybe it's
- |> a research project that will end in a year. Stop being so provincial.
-
- I do write and use long-running programs (weeks, months) that use
- multiple workstations extensively in my work.
-
- For such programs, I find that correctness and maintainability are of
- paramount importance. Efficiency, on the other hand, is of much
- less importance. If I run my program once for 9 weeks, I'm going to be
- much better off than if I speed it up by 30% but have to run it twice
- (for a total of 12 weeks) because I introduced some error.
-
- I think the idea that scientific programmers have to squeeze every last
- cycle out of their machines is a myth passed on from generation to
- generation and is out of touch with the modern economic realities of
- programming. The only people who have to squeeze every last cycle out
- of their programs are real-time programmers and software/hardware
- vendors who are concerned with looking good on benchmarks.
-
- I wouldn't care much if you make yourself unhappy by writing messy,
- unmaintainable, unportable, "optimized" code that will crawl along
- miserably once the next generation of hardware comes along. However,
- sadly, users like you are the most vocal when it comes to incorporating
- unnecessary and costly "efficiency" features into languages, operating
- systems, and hardware, and the rest of us have to pay the price
- and suffer the consequences.
-
- Thomas.
-