Infinity Fabric = PCIe

By: Michael S (, March 16, 2017 2:45 pm
Room: Moderated Discussions
Aaron Spink ( on March 16, 2017 11:24 am wrote:
> Michael S ( on March 16, 2017 8:50 am wrote:
> > [Not completely serious]
> > Intel and AMD have different philosophy for interconnects.
> > Intel likes them hot, narrow and high-latency. And very complex, please.
> > AMD prefers wide, pedestrian and under-engineered.
> > [/Not completely serious]
> >
> High latency? Um... I can state truthfully that link/phi latency was a very high significant priority.
> The actual phi latency is/was state of the art. It has been a while since I did a direct comparison
> between QPI and HT, but IIRC, QPI should have lower latency both in protocol, link, and phi layers.

First, my observation was obviously semi-humorous.

Second, it was more about memory interconnects than about processor interconnects.

Third, I don't see how, at lower protocol layers and assuming the same transfer rate, QPI could have lower latency than HT3. The two are rather similar. When there are differences, like in check sequences, QPI appears to have higher algorithmic delays. In return, it potentially has higher reliability. I say potentially, because I don't believe that bit errors rate at which the difference matters occur in real life. I believe that in real life the BER is either so low that both HT3 and QPI work fine or so high that both of them do not survive.
I don't know what happens at higher protocol layers. They are not public.
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    Infinity Fabric = PCIeslacker2017/03/15 02:59 PM
      Infinity Fabric = PCIeMichael S2017/03/15 04:19 PM
        Infinity Fabric = PCIeIreland2017/03/15 04:49 PM
        Infinity Fabric = PCIeRicardo B2017/03/15 10:25 PM
        Infinity Fabric = PCIeslacker2017/03/15 10:45 PM
          Infinity Fabric = PCIeRicardo B2017/03/15 11:02 PM
            Infinity Fabric = PCIeAaron Spink2017/03/16 01:08 AM
              Infinity Fabric = PCIeRicardo B2017/03/16 05:30 AM
                Infinity Fabric = PCIeAaron Spink2017/03/16 10:58 AM
        Infinity Fabric = PCIeGabriele Svelto2017/03/16 03:48 AM
          Latency vs. bandwidthDavid Kanter2017/03/16 08:04 AM
      Infinity Fabric = PCIeGroo2017/03/15 05:35 PM
        Infinity Fabric = PCIeslacker2017/03/15 11:11 PM
          Infinity Fabric = PCIeAdrian2017/03/16 02:51 AM
            Infinity Fabric = PCIeMichael S2017/03/16 04:32 AM
              Infinity Fabric = PCIeAdrian2017/03/16 07:58 AM
                Infinity Fabric = PCIeRicardo B2017/03/16 09:16 AM
                  Infinity Fabric = PCIeMichael S2017/03/16 09:54 AM
                    Infinity Fabric = PCIeRicardo B2017/03/16 10:07 AM
                      Infinity Fabric = PCIeMichael S2017/03/16 02:33 PM
                        Infinity Fabric = PCIeGabriele Svelto2017/03/17 03:35 AM
                          Infinity Fabric = PCIeAaron Spink2017/03/17 10:25 AM
                            Thanks, your posts on this thread have been extremely informative (NT)Gabriele Svelto2017/03/17 01:08 PM
                            Infinity Fabric = PCIeRicardo B2017/03/17 06:08 PM
                              Infinity Fabric = PCIeAaron Spink2017/03/17 06:27 PM
                              Quickpath papers - circuits and implementationslacker2017/03/18 06:50 PM
                                Quickpath papers - circuits and implementationRicardo B2017/03/19 08:07 AM
                    Infinity Fabric = PCIeAaron Spink2017/03/16 11:11 AM
                      Infinity Fabric = PCIeMichael S2017/03/16 02:46 PM
                        Infinity Fabric = PCIeRicardo B2017/03/16 03:07 PM
                          Infinity Fabric = PCIeMichael S2017/03/16 05:13 PM
                            Infinity Fabric = PCIeAaron Spink2017/03/16 11:04 PM
                            Infinity Fabric = PCIeRicardo B2017/03/16 11:30 PM
                              Infinity Fabric = PCIeMichael S2017/03/17 07:24 AM
                                Infinity Fabric = PCIeRicardo B2017/03/17 06:07 PM
              Infinity Fabric = PCIeDavid Kanter2017/03/16 08:36 AM
                Infinity Fabric = PCIeMichael S2017/03/16 08:50 AM
                  Infinity Fabric = PCIeAaron Spink2017/03/16 11:24 AM
                    Infinity Fabric = PCIeMichael S2017/03/16 02:45 PM
                      Infinity Fabric = PCIeAaron Spink2017/03/16 11:21 PM
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