FMACs can be ganged together, confirmed already by JF (link inside) -- Oh No JF

Article: AMD's Bulldozer Microarchitecture
By: redpriest (redpriest.delete@this.nospam.com), September 23, 2010 5:47 pm
Room: Moderated Discussions
David Kanter (dkanter@realworldtech.com) on 9/22/10 wrote:
---------------------------
>Anthony (someone@somedomain.com) on 9/22/10 wrote:
>---------------------------
>>>(IMHO, a shining example of why you shouldn't let marketing guys near any forum
>>>where their simplifications are taken as technical detail.)
>>
>>Thing is, he doesn't have access to, or can't disclose, >anything not already disclosed
>>elsewhere. Which means the contributions to the discussion >that are uniquely
>his are basically the stuff he gets wrong.
>
>That's not entirely true. Some of John's statements have clarified things for me...
>
>But I agree he is not someone I would turn to for technical disclosure in general.
>
>>In this case, yes, from Intel's disclosures Sandy Bridge >doesn't appear to split
>>up the SIMD hardware for legacy code. But can't Intel >issue way more SIMD instructions at once whatever the >width?
>
>I don't think this makes sense at all. There's no purpose in doing so - both AMD
>and Intel are limited by the issue capabilities of the module and core.
>
>>It sounds more like AMD wanted to make the disadvantage as >small as they could without having to use much die space.
>
>Naw, AMD got screwed on the FMA4 and 256b stuff. They made the wrong call, which
>unfortunately will cost them on FP performance.
>
>David

How? Haswell won't be on the market until late 2012. (based on Ivy Bridge late 2011). If you accept the premise that BD will be out in late 2011, then that's a year of FMA dominance.

Intel produced the FMA4 spec to "outshine" SSE5's FMA3 spec, AMD rearchitected for the 4 operand version, then Intel decided it was too hard for them to implement without schedule slip so they went with "easier" FMA3. It would be trivial to produce a version of BD in the future that supported FMA3 when Haswell is released.

Centerpiece benchmarks (other than SPEC) don't use compilers to produce AVX code, they use hand-tuned assembly. The benchmarks that will be used to showcase BD performance will all have FMA4 assembly language binaries.

Anything that is built using AVX-256 will run just fine on BD. You can tune for FMA4 for additional performance.
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TopicPosted ByDate
Bulldozer article onlineDavid Kanter2010/08/30 11:44 PM
  Bulldozer article onlineTriskaine2010/08/31 01:14 AM
  Bulldozer article online?2010/08/31 02:39 AM
    Bulldozer article onlinehobold2010/08/31 11:00 AM
    Dispatch groupsDavid Kanter2010/08/31 12:52 PM
      Dispatch groupsIntelUser20002010/08/31 02:40 PM
        Dispatch groupsDavid Kanter2010/08/31 03:22 PM
      Dispatch groupsarb2010/08/31 03:11 PM
        Dispatch groupsredpriest2010/08/31 08:46 PM
      Dispatch groups?2010/09/01 12:41 AM
        Dispatch groupsDavid Kanter2010/09/01 09:15 AM
          Dispatch groups?2010/09/01 10:03 AM
  Bulldozer article onlineAlex2010/08/31 03:45 AM
    Bulldozer article onlineIntelUser20002010/08/31 06:46 AM
      merci (NT)Alex2010/08/31 10:02 AM
    Bulldozer article onlinehobold2010/08/31 10:56 AM
      Bulldozer article onlineDavid Kanter2010/08/31 12:53 PM
  Bulldozer article onlinesomeone2010/08/31 06:09 AM
    Bulldozer article onlineIntelUser20002010/08/31 06:41 AM
      Thanks (NT)someone2010/08/31 06:52 AM
  Bulldozer article onlineRohit2010/08/31 06:13 AM
    Extremely unlikelyDaniel Bizó2010/08/31 03:00 PM
      Bulldozer versus Westmere single threaded performanceMark Roulo2010/08/31 03:35 PM
        Bulldozer versus Westmere single threaded performanceHoward Chu2010/08/31 07:25 PM
        Bulldozer versus Westmere single threaded performanceAndreas2010/09/01 01:01 AM
          Bulldozer versus Westmere single threaded performanceFoo_2010/09/01 02:11 AM
            Bulldozer versus Westmere single threaded performanceJack2010/09/01 10:08 PM
              Bulldozer versus Westmere single threaded performanceslacker2010/09/02 05:59 AM
                Bulldozer versus Westmere single threaded performanceJack2010/09/02 05:14 PM
        Bulldozer versus Westmere single threaded performanceRichard Cownie2010/09/01 04:41 AM
          Bulldozer versus Westmere single threaded performance?2010/09/01 06:10 AM
            Bulldozer versus Westmere single threaded performanceRichard Cownie2010/09/01 08:11 AM
              Bulldozer versus Westmere single threaded performanceDavid Kanter2010/09/01 08:50 AM
          Bulldozer versus Westmere single threaded performanceMark Roulo2010/09/01 09:14 AM
            Bulldozer versus Westmere single threaded performanceRichard Cownie2010/09/01 09:33 AM
      There is no 20% penalty of two threads compared to single core - it's 10%Heikki Kultala2010/09/02 10:39 PM
        There is no 20% penalty of two threads compared to single core - it's 10%Azazel2010/09/03 12:35 AM
          There is no 20% penalty of two threads compared to single core - it's 10%?2010/09/03 02:40 AM
          There is no 20% penalty of two threads compared to single core - it's 10%Heikki Kultala2010/09/03 03:49 AM
            There is no 20% penalty of two threads compared to single core - it's 10%Azazel2010/09/03 07:31 AM
          There is no 20% penalty of two threads compared to single core - it's 10%MS2010/09/03 06:27 AM
          Don't read too much into it...David Kanter2010/09/03 03:14 PM
            Don't read too much into it...DC2010/09/05 11:07 AM
  Bulldozer article onlineIan Ollmann2010/08/31 05:07 PM
    Bulldozer article onlineMatt Waldhauer2010/09/05 04:10 AM
      Bulldozer article onlinehobold2010/09/05 08:19 AM
        Bulldozer article onlineDC2010/09/05 11:12 AM
          Bulldozer article onlineMichael S2010/09/05 12:27 PM
            Bulldozer article onlineBrett2010/09/05 03:01 PM
          Bulldozer article onlinesomeone2010/09/05 01:56 PM
            Bulldozer article onlineAlex2010/09/05 02:59 PM
              Bulldozer article onlinesomeone2010/09/05 03:05 PM
                Bulldozer article onlineDC2010/09/06 07:38 AM
                  Bulldozer article onlinesomeone2010/09/06 08:24 AM
                  Bulldozer article onlineDavid Kanter2010/09/06 05:12 PM
                    Bulldozer article onlineEduardoS2010/09/06 06:21 PM
                    Bulldozer article onlineanon2010/09/06 06:26 PM
                      Bulldozer article onlineDavid Kanter2010/09/06 07:55 PM
                        Bulldozer article onlineanon2010/09/06 10:49 PM
                          Bulldozer article onlineDavid Kanter2010/09/06 10:57 PM
                            Bulldozer article onlineJack2010/09/07 09:55 PM
                            Bulldozer article onlineslacker2010/09/08 05:53 AM
            Bulldozer article onlineDC2010/09/06 07:43 AM
              Bulldozer article onlineMegol2010/09/06 08:27 AM
              Bulldozer article onlinesomeone2010/09/06 08:53 AM
                Why SOIDavid Kanter2010/09/06 05:19 PM
              Bulldozer article onlineJack2010/09/07 10:16 PM
                Bulldozer article onlineslacker2010/09/08 08:05 AM
                  Bulldozer article onlinesomeone2010/09/08 09:35 AM
                  Bulldozer article onlineJack2010/09/12 08:26 PM
                Bulldozer article onlinesomeone2010/09/08 09:03 AM
                  Some strawmen will never die (NT)slacker2010/09/08 09:13 AM
                    Yeah, like PD-SOI is worth the effort (NT)someone2010/09/08 09:39 AM
                      PDSOI is worth production dollars; FDSOI & silicon lasing are Intel's wet dreamslacker2010/09/08 10:54 AM
                  Bulldozer article onlineFritz2010/09/22 03:41 AM
                    Bulldozer article onlineanonymous2010/09/22 11:12 AM
                      Bulldozer article onlinesavantu2010/09/22 09:13 PM
      Bulldozer article onlineIan Ollmann2010/09/24 05:50 PM
        Bulldozer article onlineIan Ollmann2010/09/24 06:21 PM
          Bulldozer article onlineEduardoS2010/09/24 08:47 PM
            Bulldozer article onlineMichael S2010/09/25 10:41 AM
            Faster FADDPaul A. Clayton2010/09/25 11:58 AM
              Faster FADDEduardoS2010/09/25 12:07 PM
                Faster FADDPaul A. Clayton2010/09/28 11:29 AM
          Bulldozer article onlineMichael S2010/09/25 10:38 AM
        Bulldozer article onlineDavid Kanter2010/09/25 01:55 AM
        Bulldozer article onlineHans de Vries2010/09/26 06:58 AM
          Bulldozer article onlineDavid Kanter2010/09/26 10:38 AM
            Bulldozer article onlineHans de Vries2010/09/26 02:48 PM
              Bulldozer article onlineEduardoS2010/09/26 03:47 PM
                FP ADDs are not that fastMatt Waldhauer2010/09/30 07:46 AM
                  FP ADDs are not that fastsJ2010/09/30 11:24 AM
                    FP ADDs are not that fastEduardoS2010/09/30 01:41 PM
                      FP ADDs are not that fastrwessel2010/09/30 02:41 PM
                    FP ADDs are not that fastHans de Vries2010/09/30 07:11 PM
                  FP ADDs are not that fastEduardoS2010/09/30 01:43 PM
                    FP ADDs are not that fastMichael S2010/09/30 02:25 PM
                      FP ADDs are not that fastEduardoS2010/09/30 02:57 PM
                      FP ADDs are not that fastEric Quinnell2010/10/01 01:29 PM
                        FP ADDs are not that fastEduardoS2010/10/01 01:40 PM
                          FP ADDs are not that fastDavid Kanter2010/10/01 02:29 PM
                        Delayed post-result shift?Paul A. Clayton2010/10/01 06:14 PM
              Bulldozer article onlineDavid Kanter2010/09/26 03:50 PM
                Fusing into FMAPaul A. Clayton2010/09/27 02:01 PM
                  Fusing into FMAIan Ollmann2010/09/28 04:58 PM
                    Fusing into FMAPaul A. Clayton2010/09/29 07:25 AM
              Bulldozer article onlineMichael S2010/09/26 04:23 PM
                Bulldozer article onlineanonymous2010/09/27 01:38 AM
                  Bulldozer article onlineMichael S2010/09/27 05:00 AM
          Bulldozer article onlineEduardoS2010/09/26 10:51 AM
            Bulldozer article onlineHans de Vries2010/09/26 12:32 PM
          Bulldozer article onlineHans de Vries2010/09/26 12:28 PM
  Bulldozer article onlineMS2010/09/01 06:15 AM
  10h family 4MiB page TLB entriesPaul A. Clayton2010/09/01 06:01 PM
    10h family 4MiB page TLB entriesEduardoS2010/09/01 06:40 PM
      10h family 4MiB page TLB entriesrwessel2010/09/02 04:09 AM
        10h family 4MiB page TLB entriesEduardoS2010/09/02 03:04 PM
  Bulldozer article onlineDan Downs2010/09/02 08:28 AM
    Bulldozer article onlineslacker2010/09/02 08:37 AM
      Bulldozer article onlineDan Downs2010/09/02 10:06 AM
        Bulldozer article onlineDavid Kanter2010/09/02 04:41 PM
          Bulldozer article onlineDan Downs2010/09/02 10:42 PM
    one thread in two cores - NOHeikki Kultala2010/09/02 10:25 PM
      RF portsDavid Kanter2010/09/04 01:32 PM
  Slightly OT, but does iAtom use physical register files (PRF), too ? (NT)Alex2010/09/02 03:49 PM
    AFAIK Atom does not rename registersHeikki Kultala2010/09/03 03:46 AM
      AFAIK Atom does not rename registersAlex2010/09/03 08:41 AM
  FMACs can be ganged together, confirmed already by JF (link inside)Alex2010/09/08 04:44 PM
    FMACs can be ganged together, confirmed already by JF (link inside)David Kanter2010/09/09 07:32 AM
      FMACs can be ganged together, confirmed already by JF (link inside)Triskaine2010/09/09 07:48 AM
        FMACs can be ganged together, confirmed already by JF (link inside)David Kanter2010/09/09 08:11 AM
          FMACs can be ganged together, confirmed already by JF (link inside)arb2010/09/09 09:22 AM
            Bulldozer and AVXDavid Kanter2010/09/09 10:21 AM
          FMACs can be ganged together, confirmed already by JF (link inside)gruehunter2010/09/09 01:08 PM
            FMACs can be ganged together, confirmed already by JF (link inside)David Kanter2010/09/09 04:39 PM
              FMACs can be ganged together, confirmed already by JF (link inside)redpriest2010/09/09 09:56 PM
                FMACs can be ganged together, confirmed already by JF (link inside)Anthony2010/09/10 11:59 AM
                  FMACs can be ganged together, confirmed already by JF (link inside)someone2010/09/10 12:11 PM
      FMACs can be ganged together, confirmed already by JF (link inside)Alex2010/09/10 12:04 PM
    FMACs can be ganged together, confirmed already by JF (link inside) -- Oh No JFFritz2010/09/22 04:37 AM
      FMACs can be ganged together, confirmed already by JF (link inside) -- Oh No JFAnthony2010/09/22 11:01 AM
        FMACs can be ganged together, confirmed already by JF (link inside) -- Oh No JFDavid Kanter2010/09/22 11:22 AM
          FMACs can be ganged together, confirmed already by JF (link inside) -- Oh No JFanon2010/09/22 12:19 PM
            Bulldozer FPDavid Kanter2010/09/22 03:32 PM
              Bulldozer FPEduardoS2010/09/22 04:17 PM
                Bulldozer FPAaron Spink2010/09/23 12:13 PM
                  Bulldozer FPEduardoS2010/09/23 02:04 PM
                Bulldozer FPMichael S2010/09/23 01:26 PM
              Bulldozer FPanonymous2010/09/22 04:35 PM
              Bulldozer FPhobold2010/09/23 08:21 AM
                Bulldozer FPanon2010/09/23 11:59 AM
                  Bulldozer FPEduardoS2010/09/23 02:12 PM
                  Bulldozer FPhobold2010/09/23 02:19 PM
              Bulldozer FPHans de Vries2010/09/23 10:07 AM
                Bulldozer FPEric Bron2010/09/23 11:05 AM
          FMACs can be ganged together, confirmed already by JF (link inside) -- Oh No JFredpriest2010/09/23 05:47 PM
      FMACs can be ganged together, confirmed already by JF (link inside) -- Oh No JFAnthony2010/09/22 11:01 AM
  Bulldozer article onlineMarcal2010/09/29 03:13 AM
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