Latency and HPC Workloads

Article: Intel's Near-Threshold Voltage Computing and Applications
By: Michael S (already5chosen.delete@this.yahoo.com), October 8, 2012 1:59 pm
Room: Moderated Discussions
SHK (nomail.delete@this.mail.com) on October 8, 2012 5:42 am wrote:
> Robert Myers (rbmyersusa.delete@this.gmail.com) on October 4, 2012 10:24 am
> wrote:
>

> anon (anon.delete@this.anon.com) on October 3, 2012 6:50 pm wrote:
>
>
> >
>
> > What do you mean by latency?
> >
>
> As I have been
> involved in
> discussions, latency has always referred to the latency of memory
> references,
> whether to cache, to local memory, or to remote
> memory.
>
>
> www.sandia.gov/~rcmurph/doc/latency.pdf
>
> Robert.
>

>
> One of the things i
> really don't like in HPC since the whole "clusters take over vector processors"
> has taken place is that even the top machines on top500 are stuck with commodity
> DRAM+hardware managed caches. Everybody is complaining about the memory wall but
> something like RLDRAM-3 (AFAIK) has never been used outside networking
> equipment.
> Disregarding the physical implementation seems that a Cray T90 was a
> much better and balanced architecture for HPC.

First, you will have to convince Intel/AMD to include support for RLDRAM into their IMCs. According to my understanding, RLDRAM access protocol is substantially different from SDRAM DDR2/DDR3, or any SDRAM for that matter, so the required effort is not trivial.

Second, RLDRAM would be pretty bad for capacity, except if your opt for some form of fully buffered, which by itself adds more latency than RLDRAM saves.
If I am not mistaken, with RLDRAM you can't currently get more than 512 MB per 64bit "channel". That's like going almost full decade back. With standard unbuffered DDR3 you can easily get 8 GB per channel, with registered DDR3 - up to 96 GB/channel.




Could RLDRAM provide
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TopicPosted ByDate
New article: Intel's Near-Threshold ComputingDavid Kanter09/18/12 12:26 PM
  Higher SRAM voltage and shared L1Paul A. Clayton09/18/12 02:38 PM
    Higher SRAM voltage and shared L1David Kanter09/18/12 05:20 PM
      Higher SRAM voltage and shared L1Eric09/20/12 10:44 AM
        Higher SRAM voltage and shared L1David Kanter09/20/12 12:24 PM
      Yes, that kind of asynchronousPaul A. Clayton09/20/12 02:53 PM
    Higher SRAM voltage and shared L1somebody09/19/12 09:27 AM
      So micro-turboboost is doubly impracticalPaul A. Clayton09/20/12 02:53 PM
  Big littleDoug S09/18/12 03:04 PM
    Big littleDavid Kanter09/18/12 04:05 PM
    Big littleRicardo B09/19/12 04:06 AM
  New article: Intel's Near-Threshold Computingdefderdar09/18/12 09:39 PM
    New article: Intel's Near-Threshold Computingtarlinian09/19/12 08:32 AM
      New article: Intel's Near-Threshold ComputingDavid Kanter09/19/12 10:44 AM
  New article: Intel's Near-Threshold ComputingMark Christiansen09/19/12 11:31 AM
    New article: Intel's Near-Threshold ComputingChris Brodersen09/19/12 12:54 PM
  New article: Intel's Near-Threshold ComputingEric09/20/12 10:47 AM
  Latency and HPC WorkloadsRobert Myers10/03/12 10:52 AM
    Latency and HPC Workloadsanon10/03/12 06:50 PM
      Latency and HPC WorkloadsRobert Myers10/04/12 10:24 AM
        Latency and HPC WorkloadsSHK10/08/12 05:42 AM
          Latency and HPC WorkloadsMichael S10/08/12 01:59 PM
            Latency and HPC WorkloadsSHK10/08/12 02:42 PM
              Latency and HPC WorkloadsMichael S10/08/12 05:12 PM
                Latency and HPC Workloadsforestlaughing10/15/12 08:41 AM
                  The original context was Micron RLDRAM (NT)Michael S10/15/12 08:55 AM
                    The original context was Micron RLDRAMforestlaughing10/15/12 10:21 AM
              Latency and HPC Workloads - Why not SRAM?Kevin G10/09/12 09:48 AM
                Latency and HPC Workloads - Why not SRAM?Michael S10/09/12 10:33 AM
                  Latency and HPC Workloads - Why not SRAM?SHK10/09/12 12:55 PM
                    Why not SRAM? - CapacityRohit10/09/12 09:13 PM
                  Latency and HPC Workloads - Why not SRAM?Kevin G10/09/12 03:04 PM
                    Latency and HPC Workloads - Why not SRAM?Michael S10/09/12 04:52 PM
                      Latency and HPC Workloads - Why not SRAM?Robert Myers10/10/12 10:11 AM
                        Latency and HPC Workloads - Why not SRAM?forestlaughing10/15/12 08:02 AM
                          Latency and HPC Workloads - Why not SRAM?Robert Myers10/15/12 09:04 AM
                            Latency and HPC Workloads - Why not SRAM?forestlaughing10/16/12 09:13 AM
                          Latency and HPC Workloads - Why not SRAM?SHK10/16/12 08:12 AM
                    Latency and HPC Workloads - Why not SRAM?slacker10/11/12 01:35 PM
                      SRAM leakageDavid Kanter10/11/12 03:00 PM
          Latency and HPC Workloadsforestlaughing10/15/12 08:57 AM
            Latency and HPC WorkloadsRobert Myers10/16/12 07:28 AM
              Latency and HPC WorkloadsMichael S10/16/12 07:35 AM
              Latency and HPC Workloadsanon10/16/12 08:17 AM
                Latency and HPC WorkloadsRobert Myers10/16/12 09:56 AM
                  Supercomputer variant of Kahan quotePaul A. Clayton10/16/12 11:09 AM
                    Supercomputer variant of Kahan quoteanon10/17/12 01:17 AM
                      Supercomputer variant of Kahan quoteRobert Myers10/17/12 04:34 AM
                        Supercomputer variant of Kahan quoteanon10/17/12 05:12 AM
                          Supercomputer variant of Kahan quoteRobert Myers10/17/12 02:38 PM
                            Supercomputer variant of Kahan quoteanon10/17/12 05:24 PM
                              Supercomputer variant of Kahan quoteRobert Myers10/17/12 05:45 PM
                                Supercomputer variant of Kahan quoteanon10/17/12 05:58 PM
                                Supercomputer variant of Kahan quoteanon10/17/12 05:58 PM
                                  Supercomputer variant of Kahan quoteRobert Myers10/17/12 07:14 PM
                                    Supercomputer variant of Kahan quoteanon10/17/12 08:36 PM
                                      Supercomputer variant of Kahan quoteRobert Myers10/18/12 09:47 AM
                                        Supercomputer variant of Kahan quoteanon10/19/12 02:34 AM
                                          Supercomputer variant of Kahan quoteanon10/19/12 04:47 AM
                                          Supercomputer variant of Kahan quoteRobert Myers10/19/12 03:14 PM
                        Supercomputer variant of Kahan quoteMichael S10/17/12 06:56 PM
                          Supercomputer variant of Kahan quoteanon10/17/12 09:02 PM
                            Supercomputer variant of Kahan quoteRobert Myers10/18/12 01:29 PM
                              Supercomputer variant of Kahan quoteanon10/19/12 02:27 AM
                                Supercomputer variant of Kahan quoteRobert Myers10/19/12 07:24 AM
                                  Supercomputer variant of Kahan quoteanon10/19/12 08:00 AM
                                    Supercomputer variant of Kahan quoteRobert Myers10/19/12 09:28 AM
                                      Supercomputer variant of Kahan quoteanon10/19/12 10:27 AM
                              Supercomputer variant of Kahan quoteforestlaughing10/19/12 10:26 AM
                                Supercomputer variant of Kahan quoteRobert Myers10/19/12 07:04 PM
                                  Supercomputer variant of Kahan quoteEmil Briggs10/20/12 04:52 AM
                                    Supercomputer variant of Kahan quoteRobert Myers10/20/12 07:51 AM
                                      Supercomputer variant of Kahan quoteEmil Briggs10/20/12 08:33 AM
                                        Supercomputer variant of Kahan quoteEmil Briggs10/20/12 08:34 AM
                                          Supercomputer variant of Kahan quoteRobert Myers10/20/12 09:35 AM
                                            Supercomputer variant of Kahan quoteEmil Briggs10/20/12 10:04 AM
                                              Supercomputer variant of Kahan quoteRobert Myers10/20/12 11:23 AM
                  Latency and HPC Workloadsanon10/16/12 06:48 PM
                    Latency and HPC Workloadsforestlaughing10/19/12 11:43 AM
              Latency and HPC Workloadsforestlaughing10/19/12 09:38 AM
                Latency and HPC WorkloadsRobert Myers10/19/12 11:40 AM
                Potential false economics in researchPaul A. Clayton10/19/12 12:54 PM
                  Potential false economics in researchVincent Diepeveen10/20/12 08:59 AM
                  Potential false economics in researchforestlaughing10/23/12 10:56 AM
                    Potential false economics in researchRobert Myers10/23/12 07:16 PM
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