SPEC is NOT a representation of average workloads

By: Adrian (a.delete@this.acm.org), November 18, 2020 11:26 am
Room: Moderated Discussions
Dummond D. Slow (mental.delete@this.protozoa.us) on November 18, 2020 9:32 am wrote:
> Adrian (a.delete@this.acm.org) on November 18, 2020 9:04 am wrote:
> > Dummond D. Slow (mental.delete@this.protozoa.us) on November 18, 2020 8:41 am wrote:
> > > Adrian (a.delete@this.acm.org) on November 18, 2020 8:15 am wrote:
> > > > Dummond D. Slow (mental.delete@this.protozoa.us) on November 18, 2020 7:48 am wrote:
> > > > >
> > > > > Interesting but "long dependency chains"don't disqualify it as a benchmark, does
> > > > > it. I doubt that it is very expceptional and no other software does that.
> > > > >
> > > > > I hope eventually we get some very comparable HT/noHT CPU in AnandTech benchmark for comparing,
> > > > > in the meantime I found this https://www.anandtech.com/bench/product/2622?vs=2652
> > > > > Skylake @ 3,8-4,2GHz 4c/4t versus 4,0-4,2 4c/8t (sadly also has more L2 cache due to Intel's segmenting).
> > > >
> > > >
> > > >
> > > > A few of the workloads in which I am interested have long dependency chains,
> > > > so there are people for which such benchmarks are interesting.
> > > >
> > > >
> > > > This fact from Andrei, that Cinebench contains long dependency chains,
> > > > explains very well why M1 is less good in it than in other benchmarks.
> > > >
> > > >
> > > > Among 2 CPUs having the same average performance, a benchmark that contains
> > > > long dependency chains will favor the one having a low IPC and a high clock
> > > > frequency, against the one having a high IPC and a low clock frequency.
> > > >
> > >
> > > If you look at the single-thread score, M1 has a very high performance in it too, close
> > > to 4.7 GHz Tiger Lake. So its relative standing is not much different from where it ends
> > > up in Geekbench. It is the the regular bench-to-bench variablity, say -+5 %.
> > > Which means this is not the most important factor, as having high IPC and low clock hardly harms M1
> > > in single thread. It is the inability to exploit unused execution resources by SMT, really, which separates
> > > it from the x86 impementations in question when we look at the actual all-thread performance.
> >
> >
> > Any CPU with high IPC has the high IPC only on average.
> >
> > Any long dependency chain will have an execution time equal with the sum of the instruction
> > latencies, which will be larger for the CPU with low clock frequency, i.e. for M1.
> >
> > So normally in the benchmark with the long dependency chains
> > the IPC will be lower than in other applications,
> > unless the benchmark with the long dependency chains also
> > contains many additional operations interleaved with
> > those belonging to the long dependency chains, to fill the otherwise sub-utilized execution units.
> >
> > So, even if there are exceptions, normally the CPU having the lower clock frequency will not
> > achieve its typically higher IPC in the benchmark with many long dependency chains. While
> > the CPU with the high clock frequency is also affected, the effect is less, due to its lower
> > instruction latencies, which lead to shorter times spent in the dependency chains.
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
>
> My point was: the "long dependency chain" situation didn't make the high-IPC low-clock CPU say 50% slower
> than Zen 3. It was dunno, 10% slower in single thread, while it is say 5% faster in Geekbench (making the
> numbers up now, you can look at real values). SPEC also say they are roughly on par, up here, down here.
>
> I'm saying, M1's single thread score shows this hypothetiical effect of long dependency
> chains doesn't harm it by more than say 10 % (unless you want to argue that without it,
> M1 would be suddenly 20% faster than Zen 3 even if it is not like that elsewhere).
>
> SMT gives much bigger boost (30%+) than this on the Zen* cores, so I
> hope you see why I say it is more important of a factor in my opinion.


OK, I agree.

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TopicPosted ByDate
1st round of M1 GPU benchmarksMaynard Handley2020/11/16 01:46 PM
  1st round of M1 GPU benchmarksAdrian2020/11/16 02:02 PM
    1st round of M1 GPU benchmarksI_vs2020/11/17 02:18 AM
  1st round of M1 GPU benchmarksRType2020/11/16 02:06 PM
    1st round of M1 GPU benchmarksMaynard Handley2020/11/16 02:45 PM
      And the NZ'ers are first to deliver cinebench scoresMaynard Handley2020/11/16 03:58 PM
        And the NZ'ers are first to deliver cinebench scoresWill2020/11/16 04:30 PM
          re: "scaling"Dummond D. Slow2020/11/16 05:06 PM
            re: "scaling"Maynard Handley2020/11/16 05:29 PM
              re: "scaling"Dummond D. Slow2020/11/16 05:51 PM
                re: "scaling"Maynard Handley2020/11/16 06:51 PM
                  re: "scaling"Dummond D. Slow2020/11/16 07:22 PM
                    re: "scaling"Maynard Handley2020/11/16 07:23 PM
                      re: "scaling"Maynard Handley2020/11/16 07:27 PM
                        re: "scaling"Dummond D. Slow2020/11/16 07:37 PM
                          re: "scaling"Chester2020/11/16 09:25 PM
                          Actual power consumption values.Dummond D. Slow2020/11/17 08:05 AM
                    re: "scaling"Doug S2020/11/17 11:25 AM
                      Apple loses a lot by not having turbo and SMTDummond D. Slow2020/11/17 12:18 PM
                        Apple loses a lot by not having turbo and SMTDoug S2020/11/17 01:21 PM
                          Apple loses a lot by not having turbo and SMTblaine2020/11/19 06:18 PM
                            Apple loses a lot by not having turbo and SMTDummond D. Slow2020/11/19 06:31 PM
                        Apple loses a lot by not having turbo and SMTTJ2020/11/18 02:10 AM
                          Cinebench is NOT a representation of average workloadsAndrei F2020/11/18 06:21 AM
                            SPEC is NOT a representation of average workloadsChester2020/11/18 08:02 AM
                              SPEC is NOT a representation of average workloadsDummond D. Slow2020/11/18 08:17 AM
                                SPEC is NOT a representation of average workloadsnone2020/11/18 09:18 AM
                                  x264 without SIMD is nonsenseDummond D. Slow2020/11/18 09:31 AM
                                  SPEC is NOT a representation of average workloadsMaynard Handley2020/11/18 10:13 AM
                                    SPEC is NOT a representation of average workloadsDummond D. Slow2020/11/18 10:21 AM
                                      SPEC is NOT a representation of average workloadsWilco2020/11/18 10:42 AM
                                        role of hand-optimized assembly in multimedia encodersDummond D. Slow2020/11/18 12:06 PM
                                          role of hand-optimized assembly in multimedia encodersdifferent anon2020/11/18 02:27 PM
                                            role of hand-optimized assembly in multimedia encodersDummond D. Slow2020/11/18 03:47 PM
                                              role of hand-optimized assembly in multimedia encodersDummond D. Slow2021/05/18 01:29 PM
                                          role of hand-optimized assembly in multimedia encodersRichardC2020/11/18 04:42 PM
                                          role of hand-optimized assembly in multimedia encodersnone2020/11/19 08:17 AM
                                      SPEC is NOT a representation of average workloadsnone2020/11/18 11:14 AM
                                        SPEC is NOT a representation of average workloadsDummond D. Slow2020/11/18 12:17 PM
                                      SPEC is NOT a representation of average workloadsMaynard Handley2020/11/18 12:03 PM
                                        SPEC is NOT a representation of average workloadsDummond D. Slow2020/11/18 12:25 PM
                                          SPEC is NOT a representation of average workloadsMaynard Handley2020/11/18 01:03 PM
                                            SPEC is NOT a representation of average workloadsDummond D. Slow2020/11/18 03:57 PM
                                              SPEC is NOT a representation of average workloadsMaynard Handley2020/11/18 05:36 PM
                                                SPEC is NOT a representation of average workloadsDummond D. Slow2020/11/18 05:50 PM
                                                  SPEC is NOT a representation of average workloadsDoug S2020/11/19 10:13 AM
                                                    SPEC is NOT a representation of average workloads-.-2020/11/19 03:34 PM
                                                    SPEC is NOT a representation of average workloadsDummond D. Slow2020/11/19 03:35 PM
                                              SPEC is NOT a representation of average workloadsEtienne Lorrain2020/11/19 05:04 AM
                                                SPEC is NOT a representation of average workloadsDummond D. Slow2020/11/19 06:58 AM
                                SPEC is NOT a representation of average workloadsChester2020/11/18 03:06 PM
                                  about bitratesDummond D. Slow2020/11/18 04:04 PM
                                    about bitratesChester2020/11/19 03:45 PM
                                  SPEC is NOT a representation of average workloadsOok2020/11/18 04:05 PM
                                    SPEC is NOT a representation of average workloadsDummond D. Slow2020/11/18 04:21 PM
                                  SPEC is NOT a representation of average workloadsNoSpammer2020/11/19 07:48 AM
                              SPEC is NOT a representation of average workloadsAndrei F2020/11/18 08:44 AM
                                SPEC is NOT a representation of average workloadsDummond D. Slow2020/11/18 08:48 AM
                                  SPEC is NOT a representation of average workloadsAdrian2020/11/18 09:15 AM
                                    SPEC is NOT a representation of average workloadsDummond D. Slow2020/11/18 09:41 AM
                                      SPEC is NOT a representation of average workloadsAdrian2020/11/18 10:04 AM
                                        SPEC is NOT a representation of average workloadsDummond D. Slow2020/11/18 10:32 AM
                                          SPEC is NOT a representation of average workloadsAdrian2020/11/18 11:26 AM
                                    SPEC is NOT a representation of average workloadsMaynard Handley2020/11/18 10:22 AM
                                      SPEC is NOT a representation of average workloadsAdrian2020/11/18 11:28 AM
                                  SPEC is NOT a representation of average workloadsAndrei F2020/11/18 09:34 AM
                                    SPEC is NOT a representation of average workloadsDummond D. Slow2020/11/18 10:00 AM
                                    SPEC is NOT a representation of average workloadsChester2020/11/18 03:18 PM
                                    SPEC is NOT a representation of average workloadsJukka Larja2020/11/20 09:03 AM
                                SPEC is NOT a representation of average workloadsChester2020/11/18 03:13 PM
                              SPEC is NOT a representation of average workloadsnone2020/11/18 09:07 AM
                                SPEC is NOT a representation of average workloadsMichael S2020/11/18 02:33 PM
                                  Interesting, thanks! (NT)none2020/11/19 08:03 AM
                            Cinebench is NOT a representation of average workloadsrwessel2020/11/18 08:03 AM
                              Cinebench is NOT a representation of average workloadsDoug S2020/11/18 08:44 AM
                                Cinebench is NOT a representation of average workloadsDummond D. Slow2020/11/18 08:52 AM
                                  Cinebench is NOT a representation of average workloadsDoug S2020/11/18 03:59 PM
                                    Cinebench is NOT a representation of average workloadsDummond D. Slow2020/11/18 04:12 PM
                                      Cinebench is NOT a representation of average workloadsDoug S2020/11/19 10:19 AM
                                        Cinebench is NOT a representation of average workloadsDummond D. Slow2020/11/19 04:03 PM
                                          Cinebench is NOT a representation of average workloadsUngo2020/11/19 09:12 PM
                                            Cinebench is NOT a representation of average workloadsDummond D. Slow2020/11/20 09:45 AM
                                It's not really SMT or adding small coresDummond D. Slow2020/11/18 08:58 AM
                                  It's not really SMT or adding small coresDoug S2020/11/18 04:02 PM
                                    It's not really SMT or adding small coresDummond D. Slow2020/11/18 04:27 PM
                                Cinebench is NOT a representation of average workloadsxyz2020/11/18 01:14 PM
                                  Cinebench is NOT a representation of average workloadsMaynard Handley2020/11/18 01:54 PM
                                    Cinebench is NOT a representation of average workloadsGabriele Svelto2020/11/18 02:41 PM
                                      Cinebench is NOT a representation of average workloadsMaynard Handley2020/11/18 02:52 PM
                                        Cinebench is NOT a representation of average workloadsGabriele Svelto2020/11/18 03:05 PM
                            Cinebench is NOT a representation of average workloadsTJ2020/11/18 12:46 PM
                            SMT shines in IO heavy & commercial DB workloadsxyz2020/11/18 01:05 PM
                            "Average workloads" don't exist (NT)Foo_2020/11/19 03:55 AM
                          Apple loses a lot by not having turbo and SMTDummond D. Slow2020/11/18 08:02 AM
                            Apple loses a lot by not having turbo and SMTMaynard Handley2020/11/18 09:37 AM
                              Apple loses a lot by not having turbo and SMTDummond D. Slow2020/11/18 09:55 AM
                              Apple loses a lot by not having turbo and SMTDavid Hess2020/11/18 01:12 PM
                                Apple loses a lot by not having turbo and SMTMaynard Handley2020/11/18 02:12 PM
                                  Apple loses a lot by not having turbo and SMTJörn Engel2020/11/18 05:04 PM
                                    Apple loses a lot by not having turbo and SMTanonymou52020/11/18 05:37 PM
                                      Apple loses a lot by not having turbo and SMTJörn Engel2020/11/19 04:28 AM
                                  Apple loses a lot by not having turbo and SMTDavid Hess'2020/11/19 07:25 PM
                          Apple loses a lot by not having turbo and SMTAdrian2020/11/18 08:23 AM
                            Apple loses a lot by not having turbo and SMTgallier22020/11/19 12:21 AM
                              Apple loses a lot by not having turbo and SMTJames2020/11/19 02:22 AM
                                Apple loses a lot by not having turbo and SMTWilco2020/11/19 05:06 AM
                              Apple loses a lot by not having turbo and SMTanonymou52020/11/19 02:34 AM
                                Apple loses a lot by not having turbo and SMTgallier22020/11/19 09:04 AM
                                  big.LITTLE with different ISAsJames2020/11/19 09:41 AM
                                    big.LITTLE with different ISAsgallier22020/11/20 03:36 AM
                                    big.LITTLE with different ISAsanon2020/11/20 01:31 PM
                              Apple loses a lot by not having turbo and SMTAdrian2020/11/19 02:56 AM
                        Apple loses a lot by not having turbo and SMTJon Masters2020/11/18 12:46 PM
                          Apple loses a lot by not having turbo and SMTanonymou52020/11/18 03:41 PM
                          Apple loses a lot by not having turbo and SMTDummond D. Slow2020/11/18 04:17 PM
                            Apple loses a lot by not having turbo and SMTMaynard Handley2020/11/18 05:46 PM
                              Apple loses a lot by not having turbo and SMTJon Masters2020/11/19 12:31 AM
                                Apple loses a lot by not having turbo and SMTDummond D. Slow2020/11/19 07:01 AM
                              Apple loses a lot by not having turbo and SMTAdrian2020/11/19 02:50 AM
                                Apple loses a lot by not having turbo and SMTAdrian2020/11/19 03:10 AM
                                Apple loses a lot by not having turbo and SMTMaynard Handley2020/11/19 10:13 AM
                                  Apple loses a lot by not having turbo and SMTDummond D. Slow2020/11/19 04:10 PM
                        Apple loses a lot by not having turbo and SMTjuanrga2020/11/19 02:49 AM
                    re: "scaling"sr2020/11/17 12:39 PM
                      re: "scaling"Adrian2020/11/17 01:41 PM
                        re: "scaling"Adrian2020/11/17 01:52 PM
                          re: "scaling"Chester2020/11/17 06:29 PM
                  re: "scaling"anonymou52020/11/16 08:18 PM
                    re: "scaling"Maynard Handley2020/11/16 08:44 PM
        And the NZ'ers are first to deliver cinebench scoresDummond D. Slow2020/11/16 05:12 PM
          And the NZ'ers are first to deliver cinebench scoresMaynard Handley2020/11/16 05:31 PM
            And the NZ'ers are first to deliver cinebench scoresDummond D. Slow2020/11/16 05:46 PM
        And the NZ'ers are first to deliver cinebench scoresMaynard Handley2020/11/16 07:04 PM
          And the NZ'ers are first to deliver cinebench scoresDummond D. Slow2020/11/16 07:28 PM
  1st round of M1 GPU benchmarksRayla2020/11/16 04:16 PM
    1st round of M1 GPU benchmarksChester2020/11/16 09:17 PM
  Phoronix Mac mini M1 benchanon52020/11/20 11:51 AM
    Phoronix Mac mini M1 benchPer Hesselgren2020/11/24 10:04 AM
      Phoronix Mac mini M1 benchPaul2020/11/25 03:08 AM
        Phoronix Mac mini M1 benchPaul2020/11/25 03:12 AM
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