Zen 4c

By: Andrew Clough (someone.delete@this.somewhere.com), November 9, 2022 5:59 am
Room: Moderated Discussions
James (no.delete@this.thanks.invalid) on November 9, 2022 2:54 am wrote:
> Adrian (a.delete@this.acm.org) on November 8, 2022 11:45 am wrote:
>
Someone who would make a design from scratch of a cheaper CPU core or of a throughput-oriented CPU core...
>
So like the upcoming Zen 4c / Bergamo, but actually designed to be a smaller chip?
>
>
... would choose a width for the execution pipeline determined by the desired cost, which could be
> as low as 64-bit, or even 32-bit, and then they would implement operations with any vector width specified
> in the ISA by serial execution. This would minimize the area and the power consumption.
>
> However, in Zen 4 AMD already had pairs of identical 256-bit pipelines
> on which the 512-bit operations had to be implemented.

> Is it just me, or does that sound slightly suspicious? Like Zen 4c might drop half the
> vector units? And AMD might have been planning this going back to the re-organisation
> of the vector units in Zen 3? (AMD have said it will have the "same Zen 4 ISA".)
>
> If that was ever the plan, they would naturally design the AVX-512
> support so it didn't rely on multiple identical execution units.

Zen 4c won't have any changes like that, it'll have the same netlist as a regular Zen 4 core but with a different layout and gate sizings. It looks like the fruit of all that work they did back in the Bulldozer days for improving automated layout to be able to just re-tune an existing design to be smaller and more power efficient at the expense of clock speeds.
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TopicPosted ByDate
One 512-bit vector unit versus 2 256-bit vector units, re Zen 4 AVX-512Jeffrey Bosboom2022/11/04 06:18 PM
  Clarification?Mark Roulo2022/11/04 08:34 PM
    Expanded question about design pointsJeffrey Bosboom2022/11/04 10:37 PM
      Expanded question about design pointsAnon2022/11/04 10:53 PM
        Expanded question about design pointsJeffrey Bosboom2022/11/04 11:05 PM
          Expanded question about design pointsAnon2022/11/04 11:30 PM
            Expanded question about design pointsChester2022/11/05 04:24 PM
              Expanded question about design pointsAnon2022/11/05 04:43 PM
              Expanded question about design pointsLinus Torvalds2022/11/06 02:18 PM
                Expanded question about design pointsAdrian2022/11/07 04:38 AM
                  Expanded question about design pointsanon2022/11/07 12:34 PM
                    Expanded question about design pointsAdrian2022/11/08 04:34 AM
                      Expanded question about design pointsChester2022/11/08 08:29 AM
                      Expanded question about design pointsanon2022/11/08 09:01 AM
                        Expanded question about design pointsAdrian2022/11/08 09:53 AM
                          Expanded question about design pointsLinus Torvalds2022/11/08 11:35 AM
                            Expanded question about design pointsBrett2022/11/08 12:33 PM
                              Expanded question about design pointsBrett2022/11/08 12:48 PM
                              Expanded question about design points---2022/11/09 11:41 AM
                            Expanded question about design pointsAdrian2022/11/08 12:45 PM
                              Expanded question about design pointsLinus Torvalds2022/11/08 01:29 PM
                                Expanded question about design pointsanon2022/11/08 01:58 PM
                              Zen 4cJames2022/11/09 03:54 AM
                                Zen 4cAndrew Clough2022/11/09 05:59 AM
                                  Zen 4canonymou52022/11/09 12:29 PM
                                    Zen 4cChester2022/11/09 09:12 PM
                            Expanded question about design pointsBjörn Ragnar Björnsson2022/11/08 09:24 PM
                              FP Adders are not so cheap compared to FP multipliersHeikki Kultala2022/11/09 09:07 AM
                                FP Adders are not so cheap compared to FP multipliersBjörn Ragnar Björnsson2022/11/10 12:10 AM
                          Expanded question about design pointsAnon2022/11/08 06:31 PM
      Expanded question about design pointsAdrian2022/11/05 03:00 AM
        Expanded question about design pointsAnon2022/11/05 03:27 AM
          Expanded question about design pointsAdrian2022/11/05 03:50 AM
            Expanded question about design pointsAnon2022/11/05 04:10 AM
              Expanded question about design pointsAdrian2022/11/05 07:34 AM
        Expanded question about design pointshobold2022/11/06 04:48 AM
          Expanded question about design pointsAdrian2022/11/07 04:19 AM
            Expanded question about design pointsAdrian2022/11/07 09:07 AM
  One 512-bit vector unit versus 2 256-bit vector units, re Zen 4 AVX-512Anon2022/11/04 08:49 PM
  One 512-bit vector unit versus 2 256-bit vector units, re Zen 4 AVX-512noko2022/11/04 09:49 PM
  One 512-bit vector unit versus 2 256-bit vector units, re Zen 4 AVX-512Brendan2022/11/05 02:07 AM
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