Nehalem review up

Article: Nehalem Performance Preview
By: Michael S (already5chosen.delete@this.yahoo.com), April 11, 2009 4:12 pm
Room: Moderated Discussions
Vincent Diepeveen (diep@xs4all.nl) on 4/11/09 wrote:
---------------------------
>Michael S (already5chosen@yahoo.com) on 4/10/09 wrote:
>---------------------------
>>Vincent Diepeveen (diep@xs4all.nl) on 4/10/09 wrote:
>>---------------------------
>>>Jack (jumpingjack6@verizon.net) on 4/9/09 wrote:
>>>---------------------------
>>>>Vincent Diepeveen (diep@xs4all.nl) on 4/7/09 wrote:
>>>>
>>>>>
>>>>>How can you draw a conclusion about Shanghai, you haven't even compared it head on with Nehalem yourself.
>>>>>
>>>>>Vincent
>>>>>
>>>>
>>>>David did characterize, at the beginning of the article, that Shanghai would be
>>>>fairly characterize as slightly lagging harpertown, in that it falls behind in some
>>>>cases, achieves parity and others, and has some strong points.
>>>>
>>>>Considering that is roughly a good assessment, then it can be extrapolated that Nehalem has opened up a wide margin.
>>>>
>>>>Nonentheless, you can search the databases yourself, the 5570 DP Xeon can range
>>>>anywhere from 1.5 to 2x faster than a Shanghai 2P (2.7 GHz). I have not found one
>>>>where Shanghai even comes close. This does not make Shanghai a bad CPU, but it
>>>>does make it tough for AMD to market Shanghai against Nehalem.
>>>
>>>Sales ballony, based upon a few cracked spec tests.
>>>
>>>Both are nearly identical processors in performance for the software we tried.
>>>
>>>Of course HT and turboboost turned off, and Shanghai a tad higher clocked than
>>>E versions of Xeon, gives Shanghai a slight edge in clockrate 2.53Ghz vs 2.7 shanghai.
>>>Of course with more powerbudget intel clocks higher.
>>>
>>
>>BTW, AMD submitted SpecJbb scores for 2.9GHz Shanghai. In the past it was the
>>indication that next lower clocked part, i,e, 2.8GHz, will soon be available in
>>normal thermal envelop. So there is a hope for 2.8GHz 75W Shanghai coming.
>>
>>>If you look to the intel documents in what i7 can execute it is SSE2+ instructions
>>>a cycle max. That gives 8 flops as a max, with or without HT. Is that so much higher than AMD?
>>>
>>>Multiplication is not faster than at AMD in throughput, in fact if you try latencies
>>>of AMD are better, so a good programmer CAN be faster at AMD.
>>>
>>
>>Let's follow you own logic. Floating-point addition is faster (=had shorter latency)
>>on Intel. Should we conclude that "a good programmer CAN be faster at Intel".
>
>There is 1 unit that is doing multiplication,
>there is a lot that can do addition.
>
>Addition has a latency of 0.5 cycle at intel so to speak and 0.33 cycle or so at
>AMD (i could be off by 0.17 or so as i checked the i7 handbooks quickly a while
>ago for all kind of stuff, not the AMD ones).
>

Oh, I forgot that you don't that you don't understand the difference between latency and throughput.
Sorry.
But I didn't know that you don't understand the difference between integer and floating point addition :(
Or may be you just plain don't know that bot Intel and AMD processors have only one (admittedly, wide) FP_ADD unit - 3-clock latency on Intel, 4 on AMD?

>Multiplication is important for FFT


Do you happen to know that Radix-2 butterfly consists of 6 additions ans 4 multiplications? Do you happen to know that each dependency chain in radix-2 butterfly includes 1 multiplication and 2 additions?

>and matrix calculations.

Where only addition is a part of long dependency chain so unrolling requirements (# of accumulators) depend solely on the latency of FP addition.

>Adding goes rather
>quick. Enough units to do it. Just 1 for multiplication.

Why do you insist on talking about things you have zero clue about?

< Previous Post in ThreadNext Post in Thread >
TopicPosted ByDate
Nehalem review upDavid Kanter2009/04/07 02:43 AM
  Nehalem review upnoone2009/04/07 05:48 AM
  Strange jbb on HarpertownHenrik S2009/04/07 07:29 AM
    Strange jbb on HarpertownDavid Kanter2009/04/07 10:19 AM
      Strange jbb on HarpertownHenrik S2009/04/07 08:33 PM
        Strange jbb on HarpertownChris2009/04/07 11:54 PM
          Strange jbb on HarpertownHenrik S2009/04/08 01:40 AM
  Nehalem review upVincent Diepeveen2009/04/07 07:34 AM
    Nehalem review upJack2009/04/09 03:51 PM
      Nehalem review upVincent Diepeveen2009/04/10 12:58 AM
        Nehalem review upMichael S2009/04/10 02:45 AM
          Nehalem review upEduardoS2009/04/10 06:01 AM
            Nehalem review upMichael S2009/04/10 06:56 AM
          Nehalem review upEugene Nalimov2009/04/10 08:12 AM
          Choice of C compiler doesn't matter much for Java...Henrik S2009/04/10 09:10 AM
            Choice of C compiler doesn't matter much for Java...EduardoS2009/04/10 01:49 PM
              Choice of C compiler doesn't matter much for Java...Henrik S2009/04/11 06:13 AM
                Choice of C compiler doesn't matter much for Java...EduardoS2009/04/11 10:30 AM
                  Large pagesDavid Kanter2009/04/11 01:02 PM
                  Choice of C compiler doesn't matter much for Java...Henrik S2009/04/11 10:06 PM
                    Choice of C compiler doesn't matter much for Java...Paul2009/04/12 12:53 AM
                      Choice of C compiler doesn't matter much for Java...iz2009/04/12 01:59 AM
                      Choice of C compiler doesn't matter much for Java...Henrik S2009/04/12 06:37 AM
                    Choice of C compiler doesn't matter much for Java...EduardoS2009/04/12 07:08 AM
                      Choice of C compiler doesn't matter much for Java...Henrik S2009/04/12 08:25 AM
                        Choice of C compiler doesn't matter much for Java...EduardoS2009/04/12 04:24 PM
                          Choice of C compiler doesn't matter much for Java...Henrik S2009/04/12 09:18 PM
                            Thread costsDavid Kanter2009/04/12 11:12 PM
                              Thread costsHenrik S2009/04/14 01:08 PM
            Choice of C compiler doesn't matter much for Java...Michael S2009/04/11 07:53 AM
              Choice of C compiler doesn't matter much for Java...Henrik S2009/04/11 10:08 PM
          Nehalem review upVincent Diepeveen2009/04/11 03:50 PM
            Nehalem review upMichael S2009/04/11 04:12 PM
              Nehalem review upVincent Diepeveen2009/04/12 02:01 AM
                Nehalem review upMichael S2009/04/12 04:07 AM
  Nehalem review uprwessel2009/04/07 01:01 PM
    Nehalem review upslacker2009/04/08 08:11 AM
      Energy vs. powerDavid Kanter2009/04/08 09:11 AM
        Energy vs. powerVincent Diepeveen2009/04/10 01:08 AM
          Energy vs. powerslacker2009/04/10 08:26 AM
            Energy vs. powerRagingDragon2009/04/10 09:19 AM
              Energy vs. powerDavid Kanter2009/04/10 10:47 AM
              Energy vs. powerJack2009/04/10 03:44 PM
                Energy vs. powerslacker2009/04/10 06:00 PM
                  Energy vs. powerJack2009/04/10 06:31 PM
                  Energy vs. powerDavid Kanter2009/04/10 11:16 PM
      Nehalem review uprwessel2009/04/08 01:32 PM
  Minor font issuegpriatko2009/04/07 03:35 PM
    Minor HTML issueDavid Kanter2009/04/07 08:38 PM
      Minor HTML issueDavid Kanter2009/04/07 08:39 PM
  Good work, i look forward to linux and SP2 numbers (NT)PiedPiper2009/04/08 12:52 AM
  Nehalem review upJoe Chang2009/04/10 02:59 AM
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