Magical 100x speedups

Article: Computational Efficiency in Modern Processors
By: Linus Torvalds (torvalds.delete@this.linux-foundation.org), November 10, 2009 1:19 pm
Room: Moderated Discussions
AM (myname4rwt@jee.male) on 11/10/09 wrote:
>The highest I've seen so far is -- hold your breath! --
>4,900,000x http://www.nvidia.com/content/GTC/posters/55_Li_Fast_Evaluation_of_Helmholtz.pdf
>:-D

What bull.

I'm hoping you really meant that as a joke.

The six-and-a-half orders of magnitude difference came not
from CPU vs GPU, but from "single threaded using a very
generic and reasonably exact method" vs "multi-threaded
using another model entirely".

So the 4,900,000 times speedup is entirely in your mind,
and has nothing to do with GPU performance. It only shows
that using a different algorithm may result in different
performance. Who knew?

The actual speed-up in that paper from using the GPU vs
the CPU on the same approach was still a respectable
75-200x, but quite frankly, anybody who throws out that
five million number shows nothing but his own incompetence.

In fact, even to get the 200x number, they had to then
also accept a much lower accuracy. So even the 200x number
is pretty debatable - anybody who wants to appear at all
honest had better limit their speedups for that problem
to less.

Linus
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TopicPosted ByDate
Article: Computational Efficiency in Modern Processors by DKMoTheG2009/11/08 07:02 AM
  Article: Computational Efficiency in Modern Processors by DKnone2009/11/08 07:15 AM
  Silverthorne and OoO vs. InOrdMoTheG2009/11/08 07:22 AM
    Silverthorne and OoO vs. InOrdDavid Kanter2009/11/08 04:11 PM
      Magical 100x speedupsAM2009/11/09 09:03 AM
        Magical 100x speedupsDavid Kanter2009/11/09 12:41 PM
          Magical 100x speedupsnone2009/11/09 01:36 PM
            Magical speedupsDavid Kanter2009/11/09 03:24 PM
              Magical speedupsnone2009/11/09 03:40 PM
              Hardware SpecsMS2009/11/09 05:49 PM
                44x faster than a single cpu coreVincent Diepeveen2009/11/10 08:17 AM
              Magical speedupsVincent Diepeveen2009/11/10 08:02 AM
          Xeon 130x speedup vs XeonEric Bron2009/11/10 08:20 AM
          Magical 100x speedupsAM2009/11/10 10:42 AM
            Magical 100x speedupsLinus Torvalds2009/11/10 01:19 PM
              Mega speedupsAM2009/11/11 06:21 AM
        Bogus 100x speedupsDavid Kanter2009/11/10 01:26 AM
          No speedups for CPUs for the general programming populaceMoTheG2009/11/10 05:26 AM
          Bogus 100x speedups?2009/11/10 05:45 AM
          Bogus 100x speedupshobold2009/11/10 07:31 AM
          Bogus 100x speedupsVincent Diepeveen2009/11/10 08:26 AM
          Bogus 100x speedupssylt2009/11/10 10:00 AM
          Bogus 100x speedupsAM2009/11/10 10:47 AM
      GPU vs. CPUMoTheG2009/11/09 11:30 AM
        GPU vs. CPUa reader2009/11/09 07:58 PM
          ease of programmingMoTheG2009/11/09 11:45 PM
            yes for GPU programming you need non-public infoVincent Diepeveen2009/11/10 08:36 AM
              yes for GPU programming you need non-public infoPotatoswatter2009/11/11 08:06 AM
                yes for GPU programming you need non-public infoVincent Diepeveen2009/11/11 11:23 AM
                  yes for GPU programming you need non-public infoPotatoswatter2009/11/11 01:26 PM
                  Real businesses use GPGPU.Jouni Osmala2009/11/11 11:00 PM
        GPU vs. CPU?2009/11/10 06:01 AM
          2. try but most is said, just clarifyingMoTheG2009/11/10 10:24 AM
            2. try but most is said, just clarifying?2009/11/11 01:11 AM
              you missread meMoTheG2009/11/12 12:33 AM
                you missread me?2009/11/12 01:18 AM
            2. try but most is said, just clarifyingPotatoswatter2009/11/11 08:22 AM
              2. try but most is said, just clarifying?2009/11/12 01:22 AM
                loose, not so orderlyMoTheG2009/11/12 12:47 PM
                  loose, not so orderlyPotatoswatter2009/11/12 06:50 PM
                2. try but most is said, just clarifyingrwessel2009/11/12 01:01 PM
                  2. try but most is said, just clarifyingGabriele Svelto2009/11/13 12:39 AM
                    2. try but most is said, just clarifying?2009/11/13 01:14 AM
                      2. try but most is said, just clarifyingGabriele Svelto2009/11/13 01:30 AM
                      2. try but most is said, just clarifyingrwessel2009/11/13 01:24 PM
                  2. try but most is said, just clarifyingMichael S2009/11/14 01:08 PM
                    2. try but most is said, just clarifyingGabriele Svelto2009/11/14 11:38 PM
                      2. try but most is said, just clarifyingAndi Kleen2009/11/15 01:19 AM
                      2. try but most is said, just clarifyingMichael S2009/11/15 01:58 AM
                        2. try but most is said, just clarifyingEric Bron2009/11/15 02:25 AM
                          /MP optionEric Bron2009/11/15 02:33 AM
                            /MP optionPaul2009/11/15 09:42 AM
                              /MP optionEric Bron2009/11/15 01:22 PM
                        2. try but most is said, just clarifying?2009/11/15 03:13 AM
                          2. try but most is said, just clarifyingMichael S2009/11/15 05:14 AM
                  2. try but most is said, just clarifyingEugene Nalimov2009/11/14 09:24 PM
    Atom pointAM2009/11/09 09:00 AM
      Atom TDPDavid Kanter2009/11/09 12:48 PM
        Atom TDPhobold2009/11/10 07:41 AM
        Atom TDPAM2009/11/10 10:49 AM
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