Final note (and some remarks on Intel's paper)

Article: Parallelism at HotPar 2010
By: AM (myname4rwt.delete@this.jee-male.com), August 13, 2010 3:28 am
Room: Moderated Discussions
Apparently, Mark Roulo and David Kanter have nothing to back their statements with. No wonder, as a claim that GPU's perf advantage is limited to 2.5x-5x is as silly as Intel's infamous GPU-myth-debunking paper.

In case anyone has already forgotten or didn't care to read that piece, Intel states therein: "To the best of our knowledge, our performance numbers are at least on par and often better than the best published data."

Sounds like an almost fair bakeoff then, right? Well, at least as fair as it could be for the range of codes selected by Intel to present the myth-debunking case to the world.

They open up with "We reexamine a number of claims [9,19,21,32,42,45,47,53] that GPUs perform 10X to 1000X better than CPUs on a number of throughput kernels/applications. After tuning the code for BOTH CPU and GPU, we ?nd the GPU only performs 2.5X better than CPU." (*)

and conclude with "Our results are far less than previous claims like the 50X difference in pricing European options using Monte Carlo method [9], the 114X difference in LBM [45], the 40X difference in FFT [21], the 50X difference in sparse matrix vector multiplication [47] and the 40X difference in histogram computation [53], etc."

Aha! So all it took to accelerate original codes by a factor of tens is mere tuning of the code, even if it was done only for the CPU, which many of us would happily forgive Intel if they provided the tuned versions of the code on their website -- both in traditions of science and to promote sales of their hardware?!

Had it really been that way (and with codes made available), Intel could have scored nicely both with general public and with the folks who optimize to the last oomph for living.

Here is where the fun begins. Buried in the midst of their manuscript is the following: "For some of the kernels, we have used the best available implementation that already existed. Speci?cally, evaluations of SGEMM, SpMV, FFT and MC on GTX280 have been done using code from [1,8,2,34], respectively."

I was totally unalerted when I read the paper for the first time, as I took Intel's wording of "the best available implementation" for face value. IOW, at least as good as used in the papers they chose to debunk the myth with. Or even better.

It was almost by accident that I got back to this paper for references and some figures and found that e.g. SpMV used for comparison uses a new format (ELLPACK-R) and a new implementation, and the paper [8] by Bell and Garland used by Intel for debunking is even referenced by the authors of [47] as an existing SpMV code; that the only thing "Monte-Carlo Option Pricing" presentation by Podlozhnyuk and Harris [34] they used appears to have in common with [9] by Bennemann et al. is, well, "Monte Carlo"! Here is an excerpt from the latter, btw:

"Our implementation takes advantage of the texture memory provid-
ed by the GPU. Texture memory is accessible as a one, two or three-
dimensional lookup table, with interpolation between the nodes realized
in hardware. In Figure 3 the bilinear interpolation is depicted. Assuming
the texture map to be defined on an integer lattice, the expression

f (u, v) = (1 ? ?)(1 ? ?)f [floor(u), floor(v)] + ?(1 ? ?)f [ceil(u), floor(v)]
+(1 ? ?)?f [floor(u), ceil(v)] + ??f [ceil(u), ceil(v)]

interpolates for arbitrary real coordinates u, v, where ? and ? are the
fractional parts of the coordinates. This formula is implemented on the
hardware level within the texture addressing unit. What would corre-
spond to four separate memory fetches and several integer and floating
point operations on a normal architecture happens on the GPU at the
speed of a single memory access."


Apparently, Intel would rather "debunk" this code with some other Monte-Carlo simulation.

And even CUFFT [2] used by Intel for comparison is the GPU code authors of [21] compared theirs against. Sorry Intel, but with such methodology you don't debunk things. All you have shown is that even the codes you have personally selected to debunk the "myth" with are too good for you to deal with without resorting to such ridiculous tactics.

=========
* I'm not sure if 1000x claim was really made in any of the papers they quoted. Probably not, as otherwise Intel could have used that claim to debunk the 1000x myth instead. :)
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Tarek's Hotpar 2010 article onlineDavid Kanter2010/07/27 07:29 AM
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    Tarek's Hotpar 2010 article onlineDavid Kanter2010/07/27 10:48 PM
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                      CPU+GPU - the software problemRichard Cownie2010/08/03 05:17 AM
                        CPU+GPU - the software problemhobold2010/08/04 06:45 AM
                          NVidia in a holeRichard Cownie2010/08/04 07:23 AM
                            NVidia in a holeRohit2010/08/04 07:33 AM
                              NVidia in a holeRichard Cownie2010/08/04 07:50 AM
                                NVidia in a holeRohit2010/08/05 06:31 AM
                                  NVidia in a holeGroo2010/08/05 01:08 PM
                                NVidia in a holeGroo2010/08/05 01:07 PM
                              NVidia in a holeMark Roulo2010/08/04 08:26 AM
                                NVidia in a holeLaughabee2010/08/18 07:28 AM
                            Can nVidia survive without a sub-$100 GPU market?Mark Roulo2010/08/04 08:29 AM
                              Can nVidia survive without a sub-$100 GPU market?Richard Cownie2010/08/04 08:42 AM
                                Can nVidia survive without a sub-$100 GPU market?Mark Roulo2010/08/04 08:55 AM
                                  Can nVidia survive without a sub-$100 GPU market?Linus Torvalds2010/08/04 10:35 AM
                                    "profit" is subjectiveRichard Cownie2010/08/04 10:49 AM
                                      "profit" is subjectivea reader2010/08/06 03:54 AM
                                        no price warRichard Cownie2010/08/06 06:18 AM
                                  Can nVidia survive without a sub-$100 GPU market?Aaron Spink2010/08/04 11:19 AM
                                  Can nVidia survive without a sub-$100 GPU market?Konrad Schwarz2010/08/06 07:13 AM
                                CPU lineup != GPU lineupRohit2010/08/05 06:43 AM
                                  CPU lineup != GPU lineupRichard Cownie2010/08/05 07:12 AM
                                    CPU lineup != GPU lineupRohit2010/08/05 07:37 AM
                                      CPU lineup != GPU lineupRichard Cownie2010/08/05 07:56 AM
                                        CPU lineup != GPU lineupRohit2010/08/05 10:19 AM
                                          CPU lineup != GPU lineuphobold2010/08/06 03:08 AM
                                            CPU lineup != GPU lineupRohit2010/08/06 06:24 AM
                                              CPU lineup != GPU lineuphobold2010/08/06 06:41 AM
                              Can nVidia survive without a sub-$100 GPU market?David Hess2010/08/04 10:31 AM
                              Can nVidia survive without a sub-$100 GPU market?Ricardo B2010/08/04 12:16 PM
                              Semiconductor economicsDavid Kanter2010/08/05 08:13 AM
                                Semiconductor economicsRichard Cownie2010/08/05 08:51 AM
                                  NV buying ViA could shake up thingsRohit2010/08/05 10:09 AM
                                    NV buying ViA could shake up thingsRichard Cownie2010/08/05 10:25 AM
                                      Not likelyDavid Kanter2010/08/05 01:39 PM
                                        Not likelyrandom2010/08/05 01:49 PM
                                          Not likelyAaron Spink2010/08/05 02:18 PM
                                        Not likelyGroo2010/08/05 09:05 PM
                                        Not likelyRohit2010/08/06 06:25 AM
                                    NV buying ViA could shake up thingsGroo2010/08/05 09:02 PM
                                    NV buying ViA could shake up thingsehud2010/08/06 12:53 AM
                                      NV buying ViA could shake up thingsRohit2010/08/06 06:30 AM
                                        NV buying ViA could shake up thingsKevin G2010/08/06 04:54 PM
                                          ViA buying NV could shake up thingsBrendan2010/08/19 05:23 AM
                                        NV buying ViA could shake up thingsGroo2010/08/06 07:24 PM
                            NVidia in a holempx2010/08/04 11:01 AM
                              NVidia in a holeRichard Cownie2010/08/04 11:31 AM
                                NVidia in a holercf2010/08/04 02:40 PM
                              NVidia in a holeRohit2010/08/05 06:51 AM
                              NVidia in a holeGroo2010/08/05 08:50 PM
                              NVidia in a holeAaron Spink2010/08/05 10:52 PM
                          Anyone else wish Intel would buy Nvidia ? (NT)Silent2010/08/07 12:30 AM
                            Hell noa2010/08/07 07:37 PM
                        CPU+GPU - the software problemno thanks2010/08/04 06:54 PM
                          CPU+GPU - the software problemJouni Osmala2010/08/05 12:41 AM
                            CPU+GPU - the software problemIntelUser20002010/08/05 06:54 PM
                              CPU+GPU - the software problemJouni Osmala2010/08/05 08:36 PM
                            CPU+GPU - the software problemLinus Torvalds2010/08/06 07:08 AM
                              CPU+GPU - the software problemanonymous2010/08/06 08:39 AM
                                CPU+GPU - the software problemLinus Torvalds2010/08/06 09:56 AM
                                  non-existent Via+NV vs real OntarioRichard Cownie2010/08/06 11:12 AM
                              CPU+GPU - the software problemkoby m.2010/08/07 01:06 AM
                  CPU+GPU - the software problemhobold2010/08/03 03:48 AM
                CPU+GPU - the software problemhobold2010/08/03 03:45 AM
                  CPU+GPU - the software problemRichard Cownie2010/08/03 05:22 AM
          CPU+GPUAnon2010/07/30 08:11 PM
            CPU+GPUanon2010/07/31 02:19 AM
            CPU+GPUAaron Spink2010/08/02 05:45 PM
          100x speedups -- here we go againAM2010/08/02 12:37 AM
            100x speedups -- here we go againanon2010/08/02 02:32 AM
              100x speedups -- here we go againanon2010/08/02 10:14 PM
            GPU raw H/W only has about a 10x advantage over a CPUMark Roulo2010/08/02 08:41 AM
              GPU raw H/W only has about a 10x advantage over a CPUMichael S2010/08/02 02:31 PM
                GPU raw H/W only has about a 10x advantage over a CPUanon2010/08/02 08:36 PM
                  GPU raw H/W only has about a 10x advantage over a CPUMichael S2010/08/02 11:41 PM
                    GPU raw H/W only has about a 10x advantage over a CPUMark Roulo2010/08/03 07:22 AM
                      GPU raw H/W only has about a 10x advantage over a CPURohit2010/08/04 06:08 AM
                      There is reasonable explanation...Jouni Osmala2010/08/04 09:10 PM
                  GPU raw H/W only has about a 10x advantage over a CPUMark Roulo2010/08/03 07:19 AM
              simple reality check for youAM2010/08/03 12:45 AM
                simple reality check for younone2010/08/03 06:27 AM
                  simple reality check for youAM2010/08/03 10:50 PM
                    simple reality check for youanon2010/08/03 11:06 PM
                      simple reality check for youAM2010/08/05 02:51 AM
                        catch the same boat as everyone else next time (NT)anon2010/08/05 03:44 AM
                Simple reality checkDavid Kanter2010/08/03 07:24 AM
                  Simple reality checkGabriele Svelto2010/08/03 09:51 PM
                  Simple reality checkAM2010/08/03 10:57 PM
                    Simple reality checkanon2010/08/03 11:12 PM
                      Simple reality checkAM2010/08/05 02:59 AM
                        Simple reality checkanon2010/08/05 03:47 AM
                          Study the papers, troll (NT)AM2010/08/05 11:01 PM
                    Simple reality checkhobold2010/08/04 04:05 AM
                    Simple reality checkDean Kent2010/08/04 08:30 AM
                      Simple reality checkMark Roulo2010/08/04 08:59 AM
                      Suggestion for David Kanter and Mark RouloAM2010/08/05 02:57 AM
                        Suggestion for David Kanter and Mark Roulonone2010/08/05 03:22 AM
                          Suggestion for David Kanter and Mark RouloAM2010/08/05 11:04 PM
                        Suggestion for David Kanter and Mark Roulonone2010/08/05 03:38 AM
                          Suggestion for David Kanter and Mark Rouloanon2010/08/05 03:43 AM
                            Suggestion for David Kanter and Mark RouloAM2010/08/05 11:11 PM
                              Suggestion for David Kanter and Mark Rouloanon2010/08/06 06:52 AM
                          Suggestion for David Kanter and Mark RouloAM2010/08/05 11:10 PM
                            Suggestion for David Kanter and Mark Roulonone2010/08/06 12:35 AM
                              price doesn't matter only in theories (NT)AM2010/08/09 01:13 AM
                            Not apple4appleMichael S2010/08/06 04:13 AM
                              Not apple4appleAM2010/08/09 01:09 AM
                                Not apple4appleMichael S2010/08/09 03:35 AM
                                  Not apple4appleAM2010/08/10 12:05 AM
                                    Not apple4applenone2010/08/10 12:38 AM
                                      Back to topicAM2010/08/10 11:03 PM
                                      Final note (and some remarks on Intel's paper)AM2010/08/13 03:28 AM
                                        Final note (and some remarks on Intel's paper)none2010/08/13 08:10 AM
                                          Final note (and some remarks on Intel's paper)AM2010/08/16 12:14 AM
                                            Final note (and some remarks on Intel's paper)none2010/08/16 05:29 AM
                                              One example of 1000X shown to be wrong.sea2010/08/16 06:55 PM
                                                You're short of some factsAM2010/08/17 12:13 AM
                                                  Maybe you need to read beyond the PR statementSteve Underwood2010/08/17 01:39 AM
                                                    Maybe you need to read beyond the PR statementGroo2010/08/17 07:18 PM
                                                    check the hw they usedAM2010/08/18 02:33 AM
                                                Please realize what Monte Carlo meansVincent Diepeveen2010/08/18 02:28 AM
                                              Final note (and some remarks on Intel's paper)AM2010/08/17 12:18 AM
                                        Final note (and some remarks on Intel's paper)anon2010/08/14 12:22 AM
                                          Final note (and some remarks on Intel's paper)AM2010/08/16 12:15 AM
                                            Final note (and some remarks on Intel's paper)anon2010/08/16 01:10 PM
                                              Final note (and some remarks on Intel's paper)AM2010/08/17 12:15 AM
                                                Final note (and some remarks on Intel's paper)Michael S2010/08/17 01:58 AM
                                                  Final note (and some remarks on Intel's paper)AM2010/08/18 02:17 AM
                                                    Final note (and some remarks on Intel's paper)gallier22010/08/18 03:52 AM
                                                    Final note (and some remarks on Intel's paper)Michael S2010/08/18 04:33 AM
                                                      Final note (and some remarks on Intel's paper)Gabriele Svelto2010/08/18 05:11 AM
                                                      Final note (and some remarks on Intel's paper)Steve Underwood2010/08/18 03:03 PM
                                                        Intel might be moving from ISA to platformhobold2010/08/19 02:58 AM
                                                          Intel might be moving from ISA to platformSteve Underwood2010/08/22 06:00 PM
                                                            Intel might be moving from ISA to platformAnon2010/08/22 09:43 PM
                                                              Intel might be moving from ISA to platformajensen2010/08/22 11:37 PM
                                                                Intel might be moving from ISA to platformMichael S2010/08/23 01:13 AM
                                                                  Intel might be moving from ISA to platformSteve Underwood2010/08/23 01:35 AM
                                                                  Intel might be moving from ISA to platformhobold2010/08/26 03:37 AM
                                                                Intel might be moving from ISA to platformAnon2010/08/23 02:47 PM
                                                              Intel might be moving from ISA to platformSteve Underwood2010/08/23 01:25 AM
                                                                Intel might be moving from ISA to platformhobold2010/08/23 02:03 AM
                                                                  Intel might be moving from ISA to platformSteve Underwood2010/08/23 03:26 AM
                                                                Intel might be moving from ISA to platformAnon2010/08/23 02:55 PM
                                                                Intel might be moving from ISA to platformrwessel2010/08/23 05:41 PM
                                                                  Intel might be moving from ISA to platformSteve Underwood2010/08/23 06:30 PM
                                                                    Intel might be moving from ISA to platformrwessel2010/08/23 08:50 PM
                                                                      Intel might be moving from ISA to platformSteve Underwood2010/08/23 09:34 PM
                                                                        Intel might be moving from ISA to platformrwessel2010/08/24 12:03 AM
                                                              Intel might be moving from ISA to platformIan Ollmann2010/08/23 08:21 PM
                                                          Intel might be moving from ISA to platformajensen2010/08/22 09:36 PM
                                                            Intel might be moving from ISA to platformIan Ollmann2010/08/23 08:45 PM
                                                      Final note (and some remarks on Intel's paper)AM2010/08/19 12:29 AM
                                                        Final note (and some remarks on Intel's paper)Richard2010/08/19 03:51 AM
                                                          I stand corrected.Michael S2010/08/19 04:30 AM
                simple reality check for youanonymous2010/08/03 09:25 AM
                  simple reality check for youAM2010/08/03 10:47 PM
                    simple reality check for youanonymous2010/08/04 09:17 AM
                      simple reality check for youanon2010/08/04 07:33 PM
                      SPECint/FPAM2010/08/05 02:49 AM
                  simple reality check for youRohit2010/08/13 07:31 PM
                    simple reality check for youhobold2010/08/16 05:29 AM
              maybe texture caches ?Richard Cownie2010/08/03 08:27 AM
                maybe texture caches ?none2010/08/03 08:59 AM
                  maybe texture caches ?Richard Cownie2010/08/03 09:15 AM
                    maybe texture caches ?Mark Roulo2010/08/03 09:23 AM
                      maybe texture caches ?Richard Cownie2010/08/03 09:33 AM
                        maybe texture caches ?Mark Roulo2010/08/03 09:37 AM
                          the Hess paperRichard Cownie2010/08/03 10:16 AM
                    maybe texture caches ?Aaron Spink2010/08/03 12:23 PM
                      maybe texture caches ?Mark Roulo2010/08/03 03:13 PM
                        maybe texture caches ?Michael S2010/08/04 12:47 AM
                  maybe texture caches ?Michael S2010/08/03 09:23 AM
                maybe texture caches ?Mark Roulo2010/08/03 09:19 AM
                  maybe texture caches ?Richard Cownie2010/08/03 09:42 AM
                Cache to cache comparisonDavid Kanter2010/08/03 11:28 AM
                  Cache to cache comparisonRichard Cownie2010/08/03 11:52 AM
                    Cache to cache comparisonDavid Kanter2010/08/03 12:21 PM
                      Cache to cache comparisonRichard Cownie2010/08/03 02:55 PM
                      Cache to cache comparisonGabriele Svelto2010/08/03 10:23 PM
                        Nehalem vs Core2Richard Cownie2010/08/04 03:24 PM
                          Nehalem vs Core2IntelUser20002010/08/04 06:26 PM
                          Nehalem vs Core2Gabriele Svelto2010/08/04 09:51 PM
                            Nehalem vs Core2Richard Cownie2010/08/05 02:27 AM
                              Nehalem vs Core2Gabriele Svelto2010/08/05 05:00 AM
                                Nehalem vs Core2Richard Cownie2010/08/05 06:10 AM
                                  Nehalem vs Core2Gabriele Svelto2010/08/05 06:41 AM
                                    Nehalem vs Core2Michael S2010/08/05 09:02 AM
                              Nehalem vs Core2Michael S2010/08/05 09:12 AM
                          Nehalem vs Core2Michael S2010/08/04 11:36 PM
                            Nehalem vs Core2Richard Cownie2010/08/05 07:33 AM
                              Nehalem vs Core2Michael S2010/08/05 08:44 AM
                                Nehalem vs Core2Richard Cownie2010/08/05 09:03 AM
                                  Nehalem vs Core2Michael S2010/08/05 03:21 PM
                                    Nehalem vs Core2Richard Cownie2010/08/05 06:15 PM
                                      I'm wrong, you're right - i's 2 dieRichard Cownie2010/08/05 06:21 PM
                                    Nehalem vs Core2Richard Cownie2010/08/06 07:12 AM
                                      Nehalem vs Core2Michael S2010/08/06 07:33 AM
                                      Nehalem L1 cache latency a hedge for higher clock speeds?Mark Roulo2010/08/06 07:36 AM
                                        Nehalem L1 cache latency a hedge for higher clock speeds?Kevin G2010/08/07 09:14 AM
                                          Nehalem L1 cache latency a hedge for higher clock speeds?IntelUser20002010/08/07 01:32 PM
                                        Nehalem L1 cache latency a hedge for higher clock speeds?someone2010/08/07 01:35 PM
                          difference between C2D/C2Q chipsetsMichael S2010/08/04 11:57 PM
                          Nehalem core goals ... my takeMark Roulo2010/08/06 06:53 AM
                            Bulldozer single-threadRichard Cownie2010/08/06 03:05 PM
                          Nehalem vs Core2Carlie Coats2010/08/07 07:41 AM
                            scalingMichael S2010/08/07 10:12 AM
                            why X5460?Michael S2010/08/07 10:12 AM
                              why X5460?Carlie Coats2010/08/08 03:34 AM
                                why X5460?Michael S2010/08/08 03:42 AM
                                  Polling/PIO based COMM libraries?Michael S2010/08/08 04:14 AM
                    Cache to cache comparisonAnts Aasma2010/08/04 09:00 AM
                      Cache to cache comparisonRichard Cownie2010/08/04 09:08 AM
                        Cache to cache comparisonAnts Aasma2010/08/04 10:28 AM
                      Cache to cache comparisonMichael S2010/08/04 10:33 AM
                        Cache to cache comparisonMark Roulo2010/08/04 11:29 AM
                          Cache to cache comparisonAnts Aasma2010/08/04 12:10 PM
                            Fermi and G200 instruction latencyMark Roulo2010/08/04 01:10 PM
                              Fermi and G200 instruction latencyAnts Aasma2010/08/04 02:01 PM
                        Cache to cache comparisonAnts Aasma2010/08/04 12:00 PM
                        Register read comparisonDavid Kanter2010/08/05 08:16 AM
                          Register read comparisonGabriele Svelto2010/08/05 10:42 PM
                maybe texture caches ?Aaron Spink2010/08/03 12:17 PM
              GPU raw H/W only has about a 10x advantage over a CPURichard2010/08/09 03:58 AM
                GPU raw H/W only has about a 10x advantage over a CPUnone2010/08/09 04:19 AM
                  GPU raw H/W only has about a 10x advantage over a CPUVincent Diepeveen2010/08/24 06:18 AM
                    Forget it, they won't hear itanon2010/08/24 03:37 PM
                    GPU raw H/W only has about a 10x advantage over a CPURichard2010/08/25 12:03 PM
                This forum supports pre tagMichael S2010/08/09 05:03 AM
    Tarek's Hotpar 2010 article onlineRich Vuduc2010/07/28 09:24 AM
      Tarek's Hotpar 2010 article onlineAnon2010/07/28 03:18 PM
  Low hanging fruitMoritz2011/02/03 11:20 AM
    Low hanging fruitJukka Larja2011/02/06 04:01 AM
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