rubyinline, etc.

By: Linus Torvalds (, March 3, 2008 11:35 am
Room: Moderated Discussions
nordsieck ( on 3/2/08 wrote:
>Precisely, but that is the whole point, isn't it? There
>is no payoff to have performance that isn't in the critical

Only very simplistic problems tend to have a well-specified
"critical path".

Quite often the performance profile is not at all a matter
of one clear core operation that can be abstracted out and
rewritten in some more efficient language. At some point in
the optimization game those nice profiles just look like a
muddle of spread-out costs, and then you're stuck.

And sometimes those spread-out costs are simply things like
cache misses and memory allocation and the cost of GC (or
even the startup costs of the environment). And when that's
part of the basic language and the fundamental model you've
chosen, you're kind of screwed.

So there are definitely cases where it doesn't matter one
whit that you can do your performance-critical parts in
some more optimizable language.

Latency-critical near-RT code tends to fall into this kind
of situation. The latency of garbage collection may simply
not be acceptable, even if it may not affect performance
"on average".

Sometimes low-level languages are simply better in the
long run, and any "prototyping" in a higher-level one
should literally be considered a throw-away stage.

But you seldom know up-front whether it's worth it (or even
what the problems will be), and from a practical perspective
you may well end up being stuck with your initial choice
(even if you intended for it to be a throw-away, you
might not be able to afford to rewrite it all).

Quite frankly, anybody who says that HLL's are always the
right choice is a moron. So is anybody who says that C is
always the right choice. It depends a lot on the target,
and probably even more so on the programmers involved.

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TopicPosted ByDate
Multicore is unlikely to be the ideal answer.Anders Jensen2008/02/14 04:24 AM
  And the links..Anders Jensen2008/02/14 04:25 AM
    Disappointing..Linus Torvalds2008/02/14 10:17 AM
      Disappointing..Mark Roulo2008/02/14 11:03 AM
        LOL (NT)Linus Torvalds2008/02/14 05:43 PM
      Disappointing..David Patterson2008/02/15 11:53 AM
        Disappointing..Linus Torvalds2008/02/15 05:01 PM
          Disappointing..anon2008/02/15 08:54 PM
            Disappointing..JasonB2008/02/19 07:45 PM
          Disappointing..Ilya Lipovsky2008/02/22 06:27 PM
          Disappointing..Scott Bolt2008/03/16 11:36 AM
        Need for new programming languagesVincent Diepeveen2008/02/19 06:18 AM
          Need for new programming languagesPete Wilson2008/02/24 11:41 AM
        Disappointing..Zan2008/02/25 10:52 PM
      Disappointing..Robert Myers2008/02/19 09:47 PM
        Disappointing..Fred Bosick2008/02/22 06:38 PM
          Disappointing..Robert Myers2008/03/01 01:17 PM
        The limits of single CPU speed are here.John Nagle2008/03/14 10:55 AM
          The limits of single CPU speed are here.Howard Chu2008/03/15 01:02 AM
            The limits of single CPU speed are here.slacker2008/03/15 08:08 AM
              The limits of single CPU speed are here.Howard Chu2008/03/17 01:47 AM
                The limits of single CPU speed are here.slacker2008/03/17 10:04 AM
    And the links..Howard Chu2008/02/14 12:58 PM
      I take some of that backHoward Chu2008/02/14 01:55 PM
      And the links..Jesper Frimann2008/02/14 02:02 PM
      And the links..Ilya Lipovsky2008/02/15 02:24 PM
        And the links..iz2008/02/17 10:55 AM
          And the links..JasonB2008/02/17 07:09 PM
            And the links..Ilya Lipovsky2008/02/18 01:54 PM
              And the links..JasonB2008/02/18 10:34 PM
                And the links..Thiago Kurovski2008/02/19 07:01 PM
                  And the links..iz2008/02/20 10:36 AM
                And the links..Ilya Lipovsky2008/02/20 03:37 PM
                  And the links..JasonB2008/02/20 06:28 PM
        And the links..JasonB2008/02/17 06:47 PM
          And the links..Ilya Lipovsky2008/02/18 02:27 PM
            And the links..JasonB2008/02/18 10:00 PM
              And the links..JasonB2008/02/19 03:14 AM
              And the links..Ilya Lipovsky2008/02/20 04:29 PM
                And the links..JasonB2008/02/20 06:14 PM
                  And the links..Ilya Lipovsky2008/02/21 11:07 AM
    And the links..Howard Chu2008/02/14 01:16 PM
      And the links..Jukka Larja2008/02/15 03:00 AM
      Berkeley View on ParallelismDavid Kanter2008/02/15 11:41 AM
        Berkeley View on ParallelismHoward Chu2008/02/15 12:49 PM
          Berkeley View on ParallelismDavid Kanter2008/02/15 03:48 PM
            Berkeley View on ParallelismHoward Chu2008/02/17 05:42 PM
              Berkeley View on Parallelismnick2008/02/17 09:15 PM
                Berkeley View on ParallelismHoward Chu2008/02/18 04:23 PM
                  Berkeley View on Parallelismnick2008/02/18 10:03 PM
                    Berkeley View on ParallelismHoward Chu2008/02/19 01:39 AM
                  Berkeley View on Parallelismrcf2008/02/19 12:44 PM
                    Berkeley View on ParallelismHoward Chu2008/02/19 03:25 PM
              Average programmersanon2008/02/18 12:40 PM
        Berkeley View on ParallelismJasonB2008/02/15 08:02 PM
        Berkeley View on ParallelismJasonB2008/02/15 08:02 PM
          Berkeley View on ParallelismDean Kent2008/02/15 08:07 PM
          Berkeley View on ParallelismRay2008/02/20 03:20 PM
            Berkeley View on ParallelismJasonB2008/02/20 06:11 PM
              Berkeley View on ParallelismFritzR2008/02/24 03:08 PM
          rubyinline, etc.nordsieck2008/02/22 03:38 PM
            rubyinline, etc.JasonB2008/02/23 05:53 AM
              rubyinline, etc.nordsieck2008/03/02 01:40 AM
                rubyinline, etc.Michael S2008/03/02 02:49 AM
                  rubyinline, etc.Dean Kent2008/03/02 07:41 AM
                    rubyinline, etc.Michael S2008/03/02 08:19 AM
                      rubyinline, etc.Dean Kent2008/03/02 08:30 AM
                        rubyinline, etc.JasonB2008/03/02 05:26 PM
                rubyinline, etc.JasonB2008/03/02 06:01 PM
                  rubyinline, etc.Anonymous2008/03/03 02:11 AM
                    rubyinline, etc.JasonB2008/03/03 09:40 AM
                      rubyinline, etc.Foo_2008/03/09 09:59 AM
                        rubyinline, etc.JasonB2008/03/10 01:12 AM
                        rubyinline, etc.Gabriele Svelto2008/03/10 02:22 AM
                          rubyinline, etc.JasonB2008/03/10 04:35 AM
                            C++ for beginnersMichael S2008/03/10 05:16 AM
                              C++ for beginnersJasonB2008/03/10 06:35 AM
                          C++Michael S2008/03/10 04:55 AM
                rubyinline, etc.Linus Torvalds2008/03/03 11:35 AM
                  rubyinline, etc.Dean Kent2008/03/03 02:35 PM
                    rubyinline, etc.JasonB2008/03/03 03:57 PM
                      rubyinline, etc.Dean Kent2008/03/03 08:10 PM
                        rubyinline, etc.Michael S2008/03/04 01:53 AM
                          rubyinline, etc.Dean Kent2008/03/04 07:51 AM
                            rubyinline, etc.Michael S2008/03/04 08:29 AM
                              rubyinline, etc.Dean Kent2008/03/04 08:53 AM
                                rubyinline, etc.Michael S2008/03/04 11:20 AM
                                  rubyinline, etc.Dean Kent2008/03/04 02:13 PM
                                    read it. thanks (NT)Michael S2008/03/04 04:31 PM
                  efficient HLL'sPatrik Hägglund2008/03/04 03:34 PM
                    efficient HLL'sWes Felter2008/03/04 09:33 PM
                      efficient HLL'sPatrik Hägglund2008/03/05 01:23 AM
                        efficient HLL'sMichael S2008/03/05 02:45 AM
                          efficient HLL'sWilco2008/03/05 05:34 PM
                            efficient HLL'sHoward Chu2008/03/05 07:11 PM
                              efficient HLL'sWilco2008/03/06 02:27 PM
                    efficient HLL'sanon2008/03/05 08:20 AM
      And the links..Groo2008/02/17 04:28 PM
        And the links..Vincent Diepeveen2008/02/18 02:33 AM
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