Performance per single clock cycle

By: Doug S (foo.delete@this.bar.bar), June 16, 2022 9:39 am
Room: Moderated Discussions
hobold (hobold.delete@this.vectorizer.org) on June 16, 2022 5:12 am wrote:
> — (Canadianmist.delete@this.protonmail.com) on June 15, 2022 3:05 pm wrote:
> > anon2 (anon.delete@this.anon.com) on June 15, 2022 2:55 pm wrote:
> > > It has PPC heritage :)
> >
> > Ha. Just meant Performance Per Clock, but in a way that may be true…
>
> I was wondering for a while if maybe Apple designed a processor that can sometimes
> execute two serially dependent instructions within one longer clock cycle.
>
> How much % of cycle time is latch overhead these days? What if instead of the usual beat
> "latch work latch work latch" you built for "latch work work latch work work latch"?
>
> One probably wouldn't even try to make this work for arbitrary sequences of two dependent instructions.
> But maybe a small subset of dependent pairs is statistically dominant enough to focus on?
>


It sounds like you're suggesting something like Pentium 4's "double pumped ALU" (aka "Rapid Execution Engine")

Essentially the ALU was running at double the frequency. According to Intel that was done to make up for the Pentium 4's rather anemic IPC. Not sure how it would work on a CPU that already has very high IPC.

Running at double the frequency (even if it could be managed to enable/disable that at a whim, or have only one core doing at a time, etc.) is likely to have negative consequences for efficiency, which is one of Apple's primary design goals.
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TopicPosted ByDate
M2 benchmarks-2022/06/15 12:27 PM
  You mean "absurd ARM"? ;-) (NT)Rayla2022/06/15 02:18 PM
    It has PPC heritage :) (NT)anon22022/06/15 02:55 PM
      Performance per clock2022/06/15 03:05 PM
        Performance per single clock cyclehobold2022/06/16 05:12 AM
          Performance per single clock cycledmcq2022/06/16 06:59 AM
            Performance per single clock cyclehobold2022/06/16 07:42 AM
          Performance per single clock cycleDoug S2022/06/16 09:39 AM
            Performance per single clock cyclehobold2022/06/16 12:36 PM
            More like cascaded ALUsPaul A. Clayton2022/06/16 01:13 PM
              SuperSPARC ALUMark Roulo2022/06/16 01:57 PM
                LEABrett2022/06/16 02:52 PM
  M2 benchmarksDaveC2022/06/15 03:31 PM
    M2 benchmarksanon22022/06/15 05:06 PM
    M2 benchmarks2022/06/15 07:21 PM
    M2 benchmarks---2022/06/15 07:33 PM
  M2 benchmarksAdrian2022/06/15 10:11 PM
    M2 benchmarksEric Fink2022/06/16 12:07 AM
      M2 benchmarksAdrian2022/06/16 02:09 AM
        M2 benchmarksEric Fink2022/06/16 05:46 AM
          M2 benchmarksAdrian2022/06/16 09:27 AM
            M2 benchmarks---2022/06/16 10:08 AM
              M2 benchmarksAdrian2022/06/16 11:43 AM
                M2 benchmarksDummond D. Slow2022/06/16 01:03 PM
                  M2 benchmarksAdrian2022/06/17 03:34 AM
                    M2 benchmarksDummond D. Slow2022/06/17 07:35 AM
            M2 benchmarksnone2022/06/16 10:14 AM
              M2 benchmarksAdrian2022/06/16 12:44 PM
            M2 benchmarksEric Fink2022/06/17 02:05 AM
        M2 benchmarksAnon2022/06/16 06:28 AM
          M2 benchmarks => MTAdrian2022/06/16 11:04 AM
            M2 benchmarks => MTAnon2022/06/18 02:38 AM
              M2 benchmarks => MTAdrian2022/06/18 03:25 AM
                M2 benchmarks => MT---2022/06/18 10:14 AM
      M2 benchmarksDoug S2022/06/16 09:49 AM
        M2 Pro at 3nmEric Fink2022/06/17 02:51 AM
    M2 benchmarksSean M2022/06/16 01:00 AM
      M2 benchmarksDoug S2022/06/16 09:56 AM
        M2 benchmarksjoema2022/06/16 01:28 PM
          M2 benchmarksSean M2022/06/16 02:53 PM
            M2 benchmarksDoug S2022/06/16 09:19 PM
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                M2 benchmarks---2022/06/16 10:53 PM
                  M2 benchmarksDoug S2022/06/17 12:37 AM
                  Apple’s STEM AmbitionsSean M2022/06/17 04:18 AM
                    Apple’s STEM Ambitions---2022/06/17 09:33 AM
                      Mac Pro with Nvidia H100Tony Wu2022/06/17 06:37 PM
                        Mac Pro with Nvidia H100Doug S2022/06/17 10:37 PM
                          Mac Pro with Nvidia H100Tony Wu2022/06/18 06:49 AM
                            Mac Pro with Nvidia H100Dan Fay2022/06/18 07:40 AM
                          Mac Pro with Nvidia H100Anon42022/06/20 09:04 AM
                            Mac Pro with Nvidia H100Simon Farnsworth2022/06/20 10:09 AM
                              Mac Pro with Nvidia H100Doug S2022/06/20 10:32 AM
                                Mac Pro with Nvidia H100Simon Farnsworth2022/06/20 11:20 AM
                              Mac Pro with Nvidia H100Anon42022/06/20 04:16 PM
                            Mac Pro with Nvidia H100Doug S2022/06/20 10:19 AM
                        Mac Pro with Nvidia H100me2022/06/18 07:17 AM
                          Mac Pro with Nvidia H100Tony Wu2022/06/18 09:28 AM
                            Mac Pro with Nvidia H100me2022/06/19 10:08 AM
                              Mac Pro with Nvidia H100Dummond D. Slow2022/06/19 10:51 AM
                                Mac Pro with Nvidia H100Elliott H2022/06/19 06:39 PM
                            Mac Pro with Nvidia H100Doug S2022/06/19 06:16 PM
                              Mac Pro with Nvidia H100---2022/06/19 06:56 PM
                                Mac Pro with Nvidia H100Sam G2022/06/19 11:00 PM
                                  Mac Pro with Nvidia H100---2022/06/20 06:25 AM
                                    Mac Pro with Nvidia H100anon52022/06/20 08:41 AM
                                      Mac Pro with Nvidia H100Sam G2022/06/20 07:22 PM
                                    Mac Pro with Nvidia H100Sam G2022/06/20 07:13 PM
                                      Mac Pro with Nvidia H100Doug S2022/06/20 10:19 PM
                                        Mac Pro with Nvidia H100Sam G2022/06/22 12:06 AM
                                          Mac Pro with Nvidia H100Doug S2022/06/22 09:18 AM
                                  Mac Pro with Nvidia H100Doug S2022/06/20 10:38 AM
                                    Mac Pro with Nvidia H100Sam G2022/06/20 07:17 PM
                              Mac Pro with Nvidia H100Dummond D. Slow2022/06/20 05:46 PM
                      Apple’s STEM Ambitionsnoko2022/06/17 07:32 PM
                      Quick aside: huge pages also useful for nested page tables (virtualization) (NT)Paul A. Clayton2022/06/18 06:28 AM
                        Quick aside: huge pages also useful for nested page tables (virtualization)---2022/06/18 10:16 AM
          Not this nonsense againAnon2022/06/16 03:06 PM
            Parallel video encodingWes Felter2022/06/16 04:57 PM
              Parallel video encodingDummond D. Slow2022/06/16 07:16 PM
                Parallel video encodingWes Felter2022/06/16 07:49 PM
              Parallel video encoding---2022/06/16 07:41 PM
                Parallel video encodingDummond D. Slow2022/06/16 10:08 PM
                  Parallel video encoding---2022/06/16 11:03 PM
                    Parallel video encodingDummond D. Slow2022/06/17 07:45 AM
            Not this nonsense againjoema2022/06/16 09:13 PM
              Not this nonsense again---2022/06/16 11:18 PM
  M2 benchmarks-DDR4 vs DDR5Per Hesselgren2022/06/16 01:09 AM
    M2 benchmarks-DDR4 vs DDR5Rayla2022/06/16 08:12 AM
      M2 benchmarks-DDR4 vs DDR5Doug S2022/06/16 09:58 AM
        M2 benchmarks-DDR4 vs DDR5Rayla2022/06/16 11:58 AM
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