SP vs DP & performance metrics

Article: Computational Efficiency for CPUs and GPUs in 2012
By: anon (anon.delete@this.anon.com), July 29, 2012 2:53 am
Room: Moderated Discussions
Emil Briggs (me.delete@this.nowherespam.com) on July 28, 2012 6:11 pm wrote:
> aaron spink (aaronspink.delete@this.notearthlink.net) on July 28, 2012 7:05 am
> wrote:
> > Emil Briggs (me.delete@this.nowherespam.com) on July 28, 2012 6:40
> am
> > wrote:
> >
> > > By ORNL do you mean Oak Ridge National
> Laboratory? I ask
> > >
> > since I am a large user at ORNL. Currently
> only some of the Jaguar/Titan nodes
> >
> > > are equipped with GPU's
> but there are enough of them installed to do
> > realistic
> > >
> evaluations. For certain workloads (and when properly
> > programmed) they
> beat
> > > CPU's pretty handily performance wise. And that
> > data
> comes from a real world
> > > application not LINPACK. The section of the
>
> > code that I adapted for GPU's runs 3
> > > to 4 times faster than it
> does on
> > CPU's. It's also possible with this particular
> > >
> application to overlap some
> > operations on the CPU and GPU and hide the
> latency
> > > of PCI-E data
> > transfers. Obviously not all
> applications can benefit in the same
> > > way and
> > it's not easy to
> do so even when possible but GPU's can offer some very
> > >
> > nice
> performance gains in some cases.
> > >
> >
> > I'm not denying that
> there are
> > some workloads and some kernels that have an advantage, I am
> however saying that
> > it is generally the exception based on data published
> from both PRACE and ORNL,
> > et al.
> >
> > BTW, what % of peak are you
> seeing on the GPUs with your code?
> >
>
> There are two places where we are
> using GPU's. One of them consists of large matrix operations and are done using
> the Nvidia cublas library. Those run close to 80% of peak. The tricky part of
> the work here is keeping the CPU's busy doing something useful while moving the
> matrices back and forth to the GPU. The other place is some finite difference
> routines. Still working on this. It's faster than doing it all on the CPU's but
> not by much. I'm trying to get more overlap between the CPU and GPU's here but
> this section of the code is not as suitable for that as the first.
>
> >
> >
> > That being said I do think that the
> > > cost of moving data
> across the PCI-E
> > bus and the difficulty of the programming
> > >
> model are some real downsides
> > to GPU's. How all that plays out will be
>
> > > interesting and I'm looking
> > forward to getting my hands on
> some Intel MIC
> > > hardware to see what we can
> > do with it.
> >
> >
> >
>
> > eventually see x32/x40 PCI-E interfaces or dual QPI
> interfaces. Certainly would
> > be nice if the GPUs/MICs had simple coherent
> access to memory.
>
> Agreed. How difficult do you think it would be to implement
> coherent memory access?

Probably not all that much harder than anything else they have to do. But I would bet that neither Intel nor AMD would allow NVIDIA to implement it, so you will see it in AMD or Intel GPUs if ever.
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TopicPosted ByDate
New Article: Compute Efficiency 2012David Kanter2012/07/25 01:37 AM
  New Article: Compute Efficiency 2012SHK2012/07/25 02:31 AM
    New Article: Compute Efficiency 2012David Kanter2012/07/25 02:42 AM
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      GCN - TFLOP DPDavid Kanter2012/08/09 03:32 PM
        GCN - TFLOP DPKevin G2012/08/11 05:22 PM
      GCN - TFLOP DPEric2012/08/09 05:12 PM
        GCN - TFLOP DPjp2012/08/10 01:23 AM
          GCN - TFLOP DPEBFE2012/08/12 08:27 PM
            GCN - TFLOP DPjp2012/08/13 02:02 AM
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      New Article: Compute Efficiency 2012someone2012/07/25 10:06 AM
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        BG/QDavid Kanter2012/07/26 09:31 AM
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            VR-ZONE KNC B0 leak, poor number?Eric2012/08/03 07:59 AM
              VR-ZONE KNC B0 leak, poor number?EBFE2012/08/04 06:37 AM
                VR-ZONE KNC B0 leak, poor number?aaron spink2012/08/04 06:51 PM
                Leaks != productsDavid Kanter2012/08/05 03:19 AM
                  Leaks != productsEBFE2012/08/06 02:49 AM
                VR-ZONE KNC B0 leak, poor number?Eric2012/08/05 10:37 AM
                  VR-ZONE KNC B0 leak, poor number?EBFE2012/08/06 03:09 AM
                    VR-ZONE KNC B0 leak, poor number?aaron spink2012/08/06 04:33 AM
                      VR-ZONE KNC B0 leak, poor number?jp2012/08/07 03:08 AM
                        VR-ZONE KNC B0 leak, poor number?Eric2012/08/07 04:58 AM
                          VR-ZONE KNC B0 leak, poor number?jp2012/08/07 05:17 AM
                            VR-ZONE KNC B0 leak, poor number?Eric2012/08/07 05:22 AM
                              VR-ZONE KNC B0 leak, poor number?anonymou52012/08/07 09:43 AM
                            VR-ZONE KNC B0 leak, poor number?jp2012/08/07 05:23 AM
                              VR-ZONE KNC B0 leak, poor number?aaron spink2012/08/07 07:24 AM
                        VR-ZONE KNC B0 leak, poor number?aaron spink2012/08/07 07:20 AM
                          VR-ZONE KNC B0 leak, poor number?jp2012/08/07 11:22 AM
                            VR-ZONE KNC B0 leak, poor number?EduardoS2012/08/07 03:15 PM
                        KNC has FMADavid Kanter2012/08/07 09:17 AM
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        New Article: Compute Efficiency 2012Eric2012/07/27 12:51 PM
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        New Article: Compute Efficiency 2012anon2012/07/29 02:25 AM
          New Article: Compute Efficiency 2012hobold2012/07/29 11:53 AM
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      Best case for GPUsfranzliszt2012/07/25 01:39 PM
      Best case for GPUsChuck2012/07/25 08:13 PM
        Best case for GPUsDavid Kanter2012/07/25 09:45 PM
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  New Article: Compute Efficiency 2012Unununium2012/07/25 05:55 PM
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      Ops... I'm wrong...EduardoS2012/07/25 08:14 PM
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    Line and factorPeter Boyle2012/07/27 07:57 AM
      not entirelyMoritz2012/07/27 12:22 PM
      Line and factorEduardoS2012/07/27 05:24 PM
        Line and factorMoritz2012/07/28 12:52 PM
  tables Michael S2012/07/26 02:39 AM
  Interlagos L2+L3Rana2012/07/26 03:13 AM
    Interlagos L2+L3Rana2012/07/26 03:13 AM
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      SP vs DP & performance metricsjp2012/07/27 07:08 AM
        SP vs DP & performance metricsEric2012/07/27 07:57 AM
          SP vs DP & performance metricsjp2012/07/27 09:18 AM
            SP vs DP & performance metricsaaron spink2012/07/27 09:36 AM
              SP vs DP & performance metricsjp2012/07/27 09:47 AM
                "Global" --> systemPaul A. Clayton2012/07/27 10:31 AM
                  "Global" --> systemjp2012/07/27 03:55 PM
                    "Global" --> systemaaron spink2012/07/27 07:33 PM
                      "Global" --> systemjp2012/07/28 02:00 AM
                        "Global" --> systemaaron spink2012/07/28 06:54 AM
                          "Global" --> systemjp2012/07/29 02:12 AM
                            "Global" --> systemaaron spink2012/07/29 05:03 AM
                              "Global" --> systemnone2012/07/29 09:05 AM
                                "Global" --> systemEduardoS2012/07/29 10:26 AM
                                "Global" --> systemjp2012/07/30 02:24 AM
                                  "Global" --> systemaaron spink2012/07/30 03:05 AM
                                "Global" --> systemaaron spink2012/07/30 03:03 AM
                                  daxpy is STREAM TRIADPaul A. Clayton2012/07/30 06:10 AM
                SP vs DP & performance metricsaaron spink2012/07/27 07:25 PM
                  SP vs DP & performance metricsEmil Briggs2012/07/28 06:40 AM
                    SP vs DP & performance metricsaaron spink2012/07/28 07:05 AM
                      SP vs DP & performance metricsjp2012/07/28 11:04 AM
                        SP vs DP & performance metricsBrett2012/07/28 03:32 PM
                      SP vs DP & performance metricsEmil Briggs2012/07/28 06:11 PM
                        SP vs DP & performance metricsanon2012/07/29 02:53 AM
                        SP vs DP & performance metricsaaron spink2012/07/29 05:39 AM
                          Coherency for discretesRohit2012/07/29 09:24 AM
                          SP vs DP & performance metricsanon2012/07/29 11:09 AM
                          SP vs DP & performance metricsEric2012/07/29 01:08 PM
        SP vs DP & performance metricsaaron spink2012/07/27 09:25 AM
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            Memory power and bandwidth?David Kanter2012/08/04 11:22 AM
              Memory power and bandwidth?Michael S2012/08/04 02:36 PM
              Memory power and bandwidth?Iain McClatchie2012/08/06 02:09 PM
              Memory power and bandwidth?Eric2012/08/07 06:28 PM
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                  WorkloadsEric2012/08/09 05:21 PM
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                  Latency and bandwidth bottlenecks Eric2012/08/09 05:32 PM
                    Latency and bandwidth bottlenecks none2012/08/10 06:06 AM
                  Latency and bandwidth bottlenecks -> BDPajensen2012/08/11 03:21 PM
            Memory power and bandwidth?Ingeneer2012/08/06 11:26 AM
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    NV aims for 1.8+ TFLOPS DP ?David Kanter2012/08/11 09:25 PM
      NV aims for 1.8+ TFLOPS DP ?jp2012/08/12 02:45 AM
      NV aims for 1.8+ TFLOPS DP ?EBFE2012/08/12 10:02 PM
        NV aims for 1.8+ TFLOPS DP ?jp2012/08/13 01:54 AM
          NV aims for 1.8+ TFLOPS DP ?Gabriele Svelto2012/08/13 09:16 AM
            NV aims for 1.8+ TFLOPS DP ?Vincent Diepeveen2012/08/14 03:04 AM
          NV aims for 1.8+ TFLOPS DP ?David Kanter2012/08/13 09:50 AM
            NV aims for 1.8+ TFLOPS DP ?jp2012/08/13 11:17 AM
        NV aims for 1.8+ TFLOPS DP ?EduardoS2012/08/13 06:45 AM
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