SPEC is NOT a representation of average workloads

By: Chester (lamchester.delete@this.gmail.com), November 18, 2020 7:02 am
Room: Moderated Discussions
> 30% figure is an outlier figure for a few workloads. Across the board it's not even close to that. Can we stop
> declaring SMT an absolute must just because Cinebench has long dependency chains and scales well off of it?
>
> https://i.imgur.com/nSi11Gl.png
>
> Saying stuff like "It's simple: SMT. Had Apple implemented it, it would run away in
> Cinebench." is just idiotic in the face of the argument you want to make about SMT
> MT scaling and Apple's reasons and internal decisions about not implementing it.

Sure, Cinebench isn't the best representation of average workloads. But SPEC is far worse. No consumer cares about SPEC. The subtests are mostly based off applications no one uses, or very specific scientific simulations. It's even useless as a benchmark to see whether your system is working properly, because it's so overpriced.

Even when they base a subtest off something a consumer might do, the results are hilariously off. For example:
Encoding a 4K video using ffmpeg libx264 slow preset, on Haswell locked to 2.2 GHz
- affinity set to 4 threads: 6.6 fps
- no affinity set: 7.6 fps (1.15x scaling)

525.x264_r test: 1.0315x scaling

A quick look at the benchmark description shows them using -bitrate 1000. If that's 1 kbps (or 1 mbps) bitrate, it's hilariously unrealistic.

Now take AT Bench's POV-Ray scores for the i5-6600K (1741, 3.6 GHz all core turbo) and i7-6700K (2419, 4.2 GHz all core turbo). Scaling down the 6700K's score to account for clock speed difference gives 2073. SMT scaling would be roughly 1.19x

511.povray_r: 1.0291x scaling.

What's going on?

Also, some SPEC numbers make it seem like negative SMT scaling is common. It's not. I've personally never seen an application that can use all available threads do worse when SMT is enabled. Can we stop looking at the irrelevant pile of garbage that is SPEC?

And what makes you claim "Cinebench has long dependency chains"? How do you know SMT scaling is from that rather than hiding cache misses better? Because Cinebench (R20, have not tested R23) does suffer from L1/L2 cache misses. In ST mode, execution spends 9% of cycles stalled with a L1D miss pending. You get about 16.4 L1D MPKI if you count loads hitting the fill buffer as misses. And L2 hitrate is around 50%.
< Previous Post in ThreadNext Post in Thread >
TopicPosted ByDate
1st round of M1 GPU benchmarksMaynard Handley2020/11/16 12:46 PM
  1st round of M1 GPU benchmarksAdrian2020/11/16 01:02 PM
    1st round of M1 GPU benchmarksI_vs2020/11/17 01:18 AM
  1st round of M1 GPU benchmarksRType2020/11/16 01:06 PM
    1st round of M1 GPU benchmarksMaynard Handley2020/11/16 01:45 PM
      And the NZ'ers are first to deliver cinebench scoresMaynard Handley2020/11/16 02:58 PM
        And the NZ'ers are first to deliver cinebench scoresWill2020/11/16 03:30 PM
          re: "scaling"Dummond D. Slow2020/11/16 04:06 PM
            re: "scaling"Maynard Handley2020/11/16 04:29 PM
              re: "scaling"Dummond D. Slow2020/11/16 04:51 PM
                re: "scaling"Maynard Handley2020/11/16 05:51 PM
                  re: "scaling"Dummond D. Slow2020/11/16 06:22 PM
                    re: "scaling"Maynard Handley2020/11/16 06:23 PM
                      re: "scaling"Maynard Handley2020/11/16 06:27 PM
                        re: "scaling"Dummond D. Slow2020/11/16 06:37 PM
                          re: "scaling"Chester2020/11/16 08:25 PM
                          Actual power consumption values.Dummond D. Slow2020/11/17 07:05 AM
                    re: "scaling"Doug S2020/11/17 10:25 AM
                      Apple loses a lot by not having turbo and SMTDummond D. Slow2020/11/17 11:18 AM
                        Apple loses a lot by not having turbo and SMTDoug S2020/11/17 12:21 PM
                          Apple loses a lot by not having turbo and SMTblaine2020/11/19 05:18 PM
                            Apple loses a lot by not having turbo and SMTDummond D. Slow2020/11/19 05:31 PM
                        Apple loses a lot by not having turbo and SMTTJ2020/11/18 01:10 AM
                          Cinebench is NOT a representation of average workloadsAndrei F2020/11/18 05:21 AM
                            SPEC is NOT a representation of average workloadsChester2020/11/18 07:02 AM
                              SPEC is NOT a representation of average workloadsDummond D. Slow2020/11/18 07:17 AM
                                SPEC is NOT a representation of average workloadsnone2020/11/18 08:18 AM
                                  x264 without SIMD is nonsenseDummond D. Slow2020/11/18 08:31 AM
                                  SPEC is NOT a representation of average workloadsMaynard Handley2020/11/18 09:13 AM
                                    SPEC is NOT a representation of average workloadsDummond D. Slow2020/11/18 09:21 AM
                                      SPEC is NOT a representation of average workloadsWilco2020/11/18 09:42 AM
                                        role of hand-optimized assembly in multimedia encodersDummond D. Slow2020/11/18 11:06 AM
                                          role of hand-optimized assembly in multimedia encodersdifferent anon2020/11/18 01:27 PM
                                            role of hand-optimized assembly in multimedia encodersDummond D. Slow2020/11/18 02:47 PM
                                              role of hand-optimized assembly in multimedia encodersDummond D. Slow2021/05/18 12:29 PM
                                          role of hand-optimized assembly in multimedia encodersRichardC2020/11/18 03:42 PM
                                          role of hand-optimized assembly in multimedia encodersnone2020/11/19 07:17 AM
                                      SPEC is NOT a representation of average workloadsnone2020/11/18 10:14 AM
                                        SPEC is NOT a representation of average workloadsDummond D. Slow2020/11/18 11:17 AM
                                      SPEC is NOT a representation of average workloadsMaynard Handley2020/11/18 11:03 AM
                                        SPEC is NOT a representation of average workloadsDummond D. Slow2020/11/18 11:25 AM
                                          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 02:57 PM
                                              SPEC is NOT a representation of average workloadsMaynard Handley2020/11/18 04:36 PM
                                                SPEC is NOT a representation of average workloadsDummond D. Slow2020/11/18 04:50 PM
                                                  SPEC is NOT a representation of average workloadsDoug S2020/11/19 09:13 AM
                                                    SPEC is NOT a representation of average workloads-.-2020/11/19 02:34 PM
                                                    SPEC is NOT a representation of average workloadsDummond D. Slow2020/11/19 02:35 PM
                                              SPEC is NOT a representation of average workloadsEtienne Lorrain2020/11/19 04:04 AM
                                                SPEC is NOT a representation of average workloadsDummond D. Slow2020/11/19 05:58 AM
                                SPEC is NOT a representation of average workloadsChester2020/11/18 02:06 PM
                                  about bitratesDummond D. Slow2020/11/18 03:04 PM
                                    about bitratesChester2020/11/19 02:45 PM
                                  SPEC is NOT a representation of average workloadsOok2020/11/18 03:05 PM
                                    SPEC is NOT a representation of average workloadsDummond D. Slow2020/11/18 03:21 PM
                                  SPEC is NOT a representation of average workloadsNoSpammer2020/11/19 06:48 AM
                              SPEC is NOT a representation of average workloadsAndrei F2020/11/18 07:44 AM
                                SPEC is NOT a representation of average workloadsDummond D. Slow2020/11/18 07:48 AM
                                  SPEC is NOT a representation of average workloadsAdrian2020/11/18 08:15 AM
                                    SPEC is NOT a representation of average workloadsDummond D. Slow2020/11/18 08:41 AM
                                      SPEC is NOT a representation of average workloadsAdrian2020/11/18 09:04 AM
                                        SPEC is NOT a representation of average workloadsDummond D. Slow2020/11/18 09:32 AM
                                          SPEC is NOT a representation of average workloadsAdrian2020/11/18 10:26 AM
                                    SPEC is NOT a representation of average workloadsMaynard Handley2020/11/18 09:22 AM
                                      SPEC is NOT a representation of average workloadsAdrian2020/11/18 10:28 AM
                                  SPEC is NOT a representation of average workloadsAndrei F2020/11/18 08:34 AM
                                    SPEC is NOT a representation of average workloadsDummond D. Slow2020/11/18 09:00 AM
                                    SPEC is NOT a representation of average workloadsChester2020/11/18 02:18 PM
                                    SPEC is NOT a representation of average workloadsJukka Larja2020/11/20 08:03 AM
                                SPEC is NOT a representation of average workloadsChester2020/11/18 02:13 PM
                              SPEC is NOT a representation of average workloadsnone2020/11/18 08:07 AM
                                SPEC is NOT a representation of average workloadsMichael S2020/11/18 01:33 PM
                                  Interesting, thanks! (NT)none2020/11/19 07:03 AM
                            Cinebench is NOT a representation of average workloadsrwessel2020/11/18 07:03 AM
                              Cinebench is NOT a representation of average workloadsDoug S2020/11/18 07:44 AM
                                Cinebench is NOT a representation of average workloadsDummond D. Slow2020/11/18 07:52 AM
                                  Cinebench is NOT a representation of average workloadsDoug S2020/11/18 02:59 PM
                                    Cinebench is NOT a representation of average workloadsDummond D. Slow2020/11/18 03:12 PM
                                      Cinebench is NOT a representation of average workloadsDoug S2020/11/19 09:19 AM
                                        Cinebench is NOT a representation of average workloadsDummond D. Slow2020/11/19 03:03 PM
                                          Cinebench is NOT a representation of average workloadsUngo2020/11/19 08:12 PM
                                            Cinebench is NOT a representation of average workloadsDummond D. Slow2020/11/20 08:45 AM
                                It's not really SMT or adding small coresDummond D. Slow2020/11/18 07:58 AM
                                  It's not really SMT or adding small coresDoug S2020/11/18 03:02 PM
                                    It's not really SMT or adding small coresDummond D. Slow2020/11/18 03:27 PM
                                Cinebench is NOT a representation of average workloadsxyz2020/11/18 12:14 PM
                                  Cinebench is NOT a representation of average workloadsMaynard Handley2020/11/18 12:54 PM
                                    Cinebench is NOT a representation of average workloadsGabriele Svelto2020/11/18 01:41 PM
                                      Cinebench is NOT a representation of average workloadsMaynard Handley2020/11/18 01:52 PM
                                        Cinebench is NOT a representation of average workloadsGabriele Svelto2020/11/18 02:05 PM
                            Cinebench is NOT a representation of average workloadsTJ2020/11/18 11:46 AM
                            SMT shines in IO heavy & commercial DB workloadsxyz2020/11/18 12:05 PM
                            "Average workloads" don't exist (NT)Foo_2020/11/19 02:55 AM
                          Apple loses a lot by not having turbo and SMTDummond D. Slow2020/11/18 07:02 AM
                            Apple loses a lot by not having turbo and SMTMaynard Handley2020/11/18 08:37 AM
                              Apple loses a lot by not having turbo and SMTDummond D. Slow2020/11/18 08:55 AM
                              Apple loses a lot by not having turbo and SMTDavid Hess2020/11/18 12:12 PM
                                Apple loses a lot by not having turbo and SMTMaynard Handley2020/11/18 01:12 PM
                                  Apple loses a lot by not having turbo and SMTJörn Engel2020/11/18 04:04 PM
                                    Apple loses a lot by not having turbo and SMTanonymou52020/11/18 04:37 PM
                                      Apple loses a lot by not having turbo and SMTJörn Engel2020/11/19 03:28 AM
                                  Apple loses a lot by not having turbo and SMTDavid Hess'2020/11/19 06:25 PM
                          Apple loses a lot by not having turbo and SMTAdrian2020/11/18 07:23 AM
                            Apple loses a lot by not having turbo and SMTgallier22020/11/18 11:21 PM
                              Apple loses a lot by not having turbo and SMTJames2020/11/19 01:22 AM
                                Apple loses a lot by not having turbo and SMTWilco2020/11/19 04:06 AM
                              Apple loses a lot by not having turbo and SMTanonymou52020/11/19 01:34 AM
                                Apple loses a lot by not having turbo and SMTgallier22020/11/19 08:04 AM
                                  big.LITTLE with different ISAsJames2020/11/19 08:41 AM
                                    big.LITTLE with different ISAsgallier22020/11/20 02:36 AM
                                    big.LITTLE with different ISAsanon2020/11/20 12:31 PM
                              Apple loses a lot by not having turbo and SMTAdrian2020/11/19 01:56 AM
                        Apple loses a lot by not having turbo and SMTJon Masters2020/11/18 11:46 AM
                          Apple loses a lot by not having turbo and SMTanonymou52020/11/18 02:41 PM
                          Apple loses a lot by not having turbo and SMTDummond D. Slow2020/11/18 03:17 PM
                            Apple loses a lot by not having turbo and SMTMaynard Handley2020/11/18 04:46 PM
                              Apple loses a lot by not having turbo and SMTJon Masters2020/11/18 11:31 PM
                                Apple loses a lot by not having turbo and SMTDummond D. Slow2020/11/19 06:01 AM
                              Apple loses a lot by not having turbo and SMTAdrian2020/11/19 01:50 AM
                                Apple loses a lot by not having turbo and SMTAdrian2020/11/19 02:10 AM
                                Apple loses a lot by not having turbo and SMTMaynard Handley2020/11/19 09:13 AM
                                  Apple loses a lot by not having turbo and SMTDummond D. Slow2020/11/19 03:10 PM
                        Apple loses a lot by not having turbo and SMTjuanrga2020/11/19 01:49 AM
                    re: "scaling"sr2020/11/17 11:39 AM
                      re: "scaling"Adrian2020/11/17 12:41 PM
                        re: "scaling"Adrian2020/11/17 12:52 PM
                          re: "scaling"Chester2020/11/17 05:29 PM
                  re: "scaling"anonymou52020/11/16 07:18 PM
                    re: "scaling"Maynard Handley2020/11/16 07:44 PM
        And the NZ'ers are first to deliver cinebench scoresDummond D. Slow2020/11/16 04:12 PM
          And the NZ'ers are first to deliver cinebench scoresMaynard Handley2020/11/16 04:31 PM
            And the NZ'ers are first to deliver cinebench scoresDummond D. Slow2020/11/16 04:46 PM
        And the NZ'ers are first to deliver cinebench scoresMaynard Handley2020/11/16 06:04 PM
          And the NZ'ers are first to deliver cinebench scoresDummond D. Slow2020/11/16 06:28 PM
  1st round of M1 GPU benchmarksRayla2020/11/16 03:16 PM
    1st round of M1 GPU benchmarksChester2020/11/16 08:17 PM
  Phoronix Mac mini M1 benchanon52020/11/20 10:51 AM
    Phoronix Mac mini M1 benchPer Hesselgren2020/11/24 09:04 AM
      Phoronix Mac mini M1 benchPaul2020/11/25 02:08 AM
        Phoronix Mac mini M1 benchPaul2020/11/25 02:12 AM
Reply to this Topic
Name:
Email:
Topic:
Body: No Text
How do you spell avocado?