Nehalem review up

Article: Nehalem Performance Preview
By: Michael S (, April 10, 2009 2:45 am
Room: Moderated Discussions
Vincent Diepeveen ( on 4/10/09 wrote:
>Jack ( on 4/9/09 wrote:
>>Vincent Diepeveen ( on 4/7/09 wrote:
>>>How can you draw a conclusion about Shanghai, you haven't even compared it head on with Nehalem yourself.
>>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".
BTW, what sort of multiplication has shorter latency on AMD? I can think only about integer 64x64=>128b that is very rare in hand-coded asm and never generated by compilers.

>Yet these differences are that tiny, that any claim there of 50%+ is total ballony.

It is absolutely correct that on single-threaded dense computational kernels running out of L1/L2 cache and at the same clock frequency Intel's Merom, Penryn, Nehalem aas well as AMD's Greyhound (Barcelona) and Shanghai cores are all within few per cents +- of each other. If the kernels did not include packed SSE instructions then you could add Intel' Dothan, Yonah and AMD Hammer to the same list. Actually, in my own scalar kernels I found Nehalem rather consistently lagging behind Penryn. although that was not the case for SIMD kernels.
However that absolutely correct observation has nothing to do with the industry standard benchmarks on real CPUs that
A. Multithreaded
B. Run at different clock frequencies
C. Not dense
D. Could fit in onchip cache on one CPU but not on another (that what hurts Bracelona most)

Points A+C and D give big edge to Nehalem because it has both SMT and much faster external memory access than any of competitors.

>It's just compiler and L3 based all these claims for just a few software programs.
>If you see clearly how moving from intel c++ 10.0 to 11.0 is a huge improvement
>at core2 already, obviously the compiler team did do a great job.

Are you sure that Oracle and IBM JVMs compiled with Intel compiler?

>I see i7 as a very logical step from core2, yet for performance a tiny step, if
>you look single socket. Of course this allows intel now to scale to 2 and maybe soon 4 sockets.
>>However, if you are truly interested in how Nehalem stacks up against Shanghai,
>>you can search the following, scores for both processors are now in the database:
>A $100 billion company, well it used to be, that just gets benchmarked for a few
>programs, that's not a rather good idea.
>Turboboost, HT, more power budget, it sure helps to look better.
>It's not a help in practice; the X series that eat so much more power, that these
>can increase their clockfrequency a lot more with turboboost than the E series,
>whereas all HPC centers will be buying nearly always the E series and some, also
>datacenters, already announced turboboost will get turned off. If i look at ebay
>now, the L series 54xx still are a lot more expensive than the E series, how comes?
>>Also, using a QX9770 in the comparision is not a bad idea, but it is also not a
>>server branded CPU. It is irrelevant anyway, a few hundred MHz won't change the result.
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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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