What is next after DDR5?

By: David Hess (davidwhess.delete@this.gmail.com), April 4, 2021 8:52 pm
Room: Moderated Discussions
Andrey (andrey.semashev.delete@this.gmail.com) on March 30, 2021 9:09 am wrote:
> Anononymous Coward (anonymous.delete@this.coward.net) on March 30, 2021 7:03 am wrote:
> > > DDR5 will allow you to use effectively 2x the core count because it will eventually result in
> > > ~2x bandwidth (3200 -> 6400 and bandwidth efficiency improvements).
> >
> > No. For all practical purposes you are limited by latency and not by bandwidth.
>
> There is some amount of bandwidth that a workload benefits the most. If that bandwidth requirement
> is satisfied then you may benefit more from latency reduction. The bandwidth is divided between cores,
> so the more cores you have the more total bandwidth you need. That optimal bandwidth threshold is
> specific to each workload, and some workloads are more sensitive to bandwidth than others.

Doubling the bandwidth of DDR5 is not that simple. The total bandwidth is doubled, but the channel width is halved to 32 bits and there are twice as many channels. So the real improvement is doubling the number of channels while each channel has the same bandwidth, and about the same latency, as DDR4. With twice as many channels, twice as many memory transactions can be in progress.
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Intel's IDM 2.0 announcementJon Masters2021/03/23 03:31 PM
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    Intel's IDM 2.0 announcementdmcq2021/03/23 04:30 PM
    commitment to foundry, shutting down fabless talkDaniel B2021/03/23 04:46 PM
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        commitment to foundry, shutting down fabless talkanonymou52021/03/24 12:57 AM
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              commitment to foundry, shutting down fabless talkMichael S2021/03/24 06:47 AM
                commitment to foundry, shutting down fabless talkme2021/03/24 07:04 AM
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          Intel gutted 7 nmDoug S2021/03/24 08:20 AM
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                  Intel gutted 7 nmwumpus2021/03/26 09:53 AM
                  Intel gutted 7 nmme2021/03/26 10:11 AM
                  Intel gutted 7 nmMaxwell2021/03/26 02:21 PM
                    Intel gutted 7 nmYoav2021/03/29 01:06 AM
              Intel gutted 7 nmDoug S2021/03/26 09:43 AM
                Intel gutted 7 nmanon2021/03/26 03:39 PM
                  Intel gutted 7 nmNoSpammer2021/03/26 08:46 PM
                    Intel gutted 7 nmAdrian2021/03/26 11:57 PM
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                    Intel gutted 7 nmanon2021/03/27 05:52 AM
                    Intel gutted 7 nmwumpus2021/03/27 12:16 PM
                  Intel gutted 7 nmDoug S2021/03/27 05:08 PM
                    Intel gutted 7 nmanon2021/12/13 03:05 PM
                      Intel gutted 7 nm---2021/12/13 04:31 PM
                      Intel gutted 7 nmDoug S2021/12/13 09:34 PM
                        Intel gutted 7 nmanon2021/12/13 10:41 PM
                          Intel gutted 7 nmDoug S2021/12/14 11:38 AM
                            Intel gutted 7 nmanon2021/12/14 11:58 AM
                            Feed the Troll less (unless you are enjoying it!)Mark Roulo2021/12/14 01:52 PM
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                  Intel gutted 7 nmme2021/03/27 12:22 PM
                  Intel gutted 7 nmDoug S2021/03/27 05:14 PM
                    Intel gutted 7 nmDavid Kanter2021/04/07 09:06 PM
                      Intel gutted 7 nmDoug S2021/04/08 12:38 PM
        commitment to foundry, shutting down fabless talkDaniel B2021/03/24 08:08 AM
      commitment to foundry, shutting down fabless talkDoug S2021/03/24 08:12 AM
      commitment to foundry, shutting down fabless talkMaxwell2021/03/25 11:16 AM
        commitment to foundry, shutting down fabless talkme2021/03/25 11:38 AM
          commitment to foundry, shutting down fabless talkAdrian2021/03/25 01:01 PM
            commitment to foundry, shutting down fabless talkme2021/03/27 12:57 PM
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    Intel's IDM 2.0 announcementGabriele Svelto2021/03/25 03:17 AM
  Intel's IDM 2.0 announcementBeastian2021/03/23 05:39 PM
    Intel's IDM 2.0 announcementJames2021/03/24 03:14 AM
      Intel's IDM 2.0 announcementme2021/03/24 03:37 AM
        Intel's IDM 2.0 announcementJames2021/03/24 03:53 AM
      Intel's IDM 2.0 announcementanonymou52021/03/24 08:39 AM
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    Intel's IDM 2.0 announcement - Hyper-scalers as customersBjörn Ragnar Björnsson2021/03/24 06:19 PM
  5nm the end of DRAM?Brett2021/03/25 05:17 PM
    What is next after DDR5?Ganon2021/03/25 05:56 PM
      What is next after DDR5?wumpus2021/03/26 09:10 AM
        What is next after DDR5?Brett2021/03/26 04:39 PM
          What is next after DDR5?wumpus2021/03/28 10:44 AM
      What is next after DDR5?Brett2021/03/27 04:27 PM
        What is next after DDR5?Doug S2021/03/27 05:18 PM
      What is next after DDR5?Anononymous Coward2021/03/30 07:03 AM
        What is next after DDR5?Andrey2021/03/30 09:09 AM
          What is next after DDR5?David Hess2021/04/04 08:52 PM
      What is next after DDR5?David Hess2021/04/04 08:45 PM
        What is next after DDR5?Doug S2021/04/05 06:57 AM
          What is next after DDR5?David Hess2021/04/05 10:45 AM
          Same costAnon2021/04/05 11:31 AM
            Same costDavid Hess2021/04/05 08:26 PM
            Same costMaxwell2021/04/06 07:17 PM
              Same costDavid Hess2021/04/07 02:35 PM
          What is next after DDR5?wumpus2021/04/07 09:06 AM
      L4 is not a memory technologyHeikki Kultala2021/04/07 12:38 PM
        DRAM cachewumpus2021/04/08 08:24 AM
        Intel iGPU memory was eDRAM, not SRAMMark Roulo2021/04/08 11:31 AM
          I am not talking about the eDRAM. I am talking about the cache that is L3 for CPUHeikki Kultala2021/04/08 11:09 PM
            I am not talking about the eDRAM. I am talking about the cache that is L3 for CPURobert Williams2021/04/09 11:24 AM
              This STILL has NOTHING to do with the eDRAM. I am talking about the SRAM LLCHeikki Kultala2021/04/09 12:57 PM
                This STILL has NOTHING to do with the eDRAM. I am talking about the SRAM LLC---2021/04/09 01:40 PM
    5nm the end of DRAM?Rayla2021/03/26 09:28 AM
      5nm the end of DRAM?riy2021/04/08 06:26 AM
        5nm the end of DRAM?Michael S2021/04/08 11:51 AM
    5nm the end of DRAM?Doug S2021/03/26 09:52 AM
      5nm the end of DRAM?wumpus2021/04/07 09:10 AM
        5nm the end of DRAM?Robert Williams2021/04/07 11:05 AM
    Totaly misunderstanding of DDR SDRAM memory interfaces and DRAMHeikki Kultala2021/04/07 12:36 PM
      Totaly misunderstanding of DDR SDRAM memory interfaces and DRAManonymou52021/04/07 01:13 PM
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