New article - The Common System Interface: Intel's Future Interconnect

Article: The Common System Interface: Intel's Future Interconnect
By: David Kanter (dkanter.delete@this.realworldtech.com), August 28, 2007 12:43 pm
Room: Moderated Discussions
Paul (no@thanks.com) on 8/28/07 wrote:
---------------------------
>David Kanter (dkanter@realworldtech.com) on 8/28/07 wrote:
>---------------------------
>>I hope you all enjoy the read. I'd also like to thank everyone who helped with
>>this article. I relied on the technical expertise of quite a few friends, and
>>without their help this article wouldn't be nearly as compete or understandable.
>
>Regarding Xeon MPs and cache size you usually do need more >cache the more processors
>you put on an SMP node. Any thread may be scheduled on any processor as each processor
>has to have the working sets for all the threads in cache >unless you want to wait for a fill from memory.

I agree.

>I don't know how Opteron gets away with its L2 caches being small. Some of it is
>probably declaring that it's a NUMA system to the OS so it takes CPU affinity into
>account when making scheduling decisions.

Low memory latency for local stuff is probably the answer. Although some cache-happy benchmarks like SPECjbb really do suffer.

>Does Opteron do anything like have the memory requests for >a line fill from a remote
>processor be serviced from within the L2 cache so you can >essentially shuttle working
>sets between L2 caches and not have to go to memory?

It depends on what state the line is in. In general, I believe the Opteron coherency protocol requires that the requesting processor receive all responses (from caching agents and the home node) before using data.

This may not be the case if the data is in a dirty cache line, but I'm not 100% sure, since AMD's protocol is not particularly open to the public.

DK
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TopicPosted ByDate
New article - The Common System Interface: Intel's Future InterconnectDavid Kanter2007/08/28 01:16 AM
  New article - The Common System Interface: Intel's Future InterconnectVincent Diepeveen2007/08/28 05:02 AM
  New article - The Common System Interface: Intel's Future InterconnectRichard Cownie2007/08/28 10:28 AM
    New article - The Common System Interface: Intel's Future InterconnectVincent Diepeveen2007/08/31 11:44 AM
      New article - The Common System Interface: Intel's Future InterconnectRichard Cownie2007/08/31 08:53 PM
        New article - The Common System Interface: Intel's Future InterconnectVincent Diepeveen2007/09/01 02:21 AM
          Adding layers can simplify designPaul A. Clayton2007/09/01 07:39 AM
          New article - The Common System Interface: Intel's Future InterconnectMichael S2007/09/02 02:25 AM
        New article - The Common System Interface: Intel's Future InterconnectJonathan Kang2007/09/14 12:47 PM
    New article - The Common System Interface: Intel's Future InterconnectDavid Kanter2007/09/14 08:47 PM
  New article - The Common System Interface: Intel's Future InterconnectPaul2007/08/28 11:04 AM
    New article - The Common System Interface: Intel's Future InterconnectDavid Kanter2007/08/28 12:43 PM
      New article - The Common System Interface: Intel's Future InterconnectJoe Chang2007/08/28 06:17 PM
        New article - The Common System Interface: Intel's Future InterconnectJoe Chang2007/08/29 04:27 PM
  Thanks for the workWouter Tinus2007/08/28 12:33 PM
    Thanks for the workmac2007/08/29 12:44 PM
  New article - The Common System Interface: Intel's Future InterconnectHerbert Hum2007/08/28 01:22 PM
    ThanksDavid Kanter2007/08/28 04:13 PM
  Many thanks, very, very interesting! (NT)Cameron Jack2007/08/29 01:51 AM
  very nice article + memory ctrl integrationMarcin Niewiadomski2007/08/29 11:46 AM
    very nice article + memory ctrl integrationDavid Kanter2007/09/14 08:50 PM
      very nice article + memory ctrl integrationMarcin Niewiadomski2007/09/16 08:48 PM
  Coherency: Forwarding and OwnedPeter Gerdes2007/08/29 02:11 PM
    Coherency: Forwarding and OwnedDavid Kanter2007/08/29 06:29 PM
      Coherency: Forwarding and Ownednick2007/08/29 07:03 PM
        Coherency: Forwarding and OwnedDavid Kanter2007/08/29 11:08 PM
      Coherency: Forwarding and OwnedMichael S2007/08/30 01:17 AM
        Coherency: Forwarding and OwnedDavid Kanter2007/08/30 07:31 AM
      Coherency: Forwarding and OwnedPeter Gerdes2007/08/30 11:46 AM
        Coherency: Forwarding and OwnedDavid Kanter2007/08/30 01:46 PM
          Coherency: Forwarding and OwnedPeter Gerdes2007/08/30 07:03 PM
            Coherency: Forwarding and OwnedDavid Kanter2007/09/14 08:44 PM
              Node Interleaveunknown2007/09/15 03:14 AM
                Node InterleaveDavid Kanter2007/09/15 07:50 AM
                  Node InterleaveHoward Chu2007/09/16 12:14 PM
              Coherency: Forwarding and OwnedPeter Gerdes2007/09/16 12:50 PM
                Coherency: Forwarding and OwnedDavid Kanter2007/09/16 04:34 PM
                  Coherency: Forwarding and OwnedEduardoS2007/09/16 04:52 PM
                  Coherency: Forwarding and OwnedJonathan Kang2007/09/17 05:16 AM
                  Coherency: Forwarding and OwnedMatthias2007/09/17 06:59 AM
                    Coherency: Forwarding and Owned - additionMatthias2007/09/17 07:01 AM
                Coherency: Forwarding and Ownedanonymous2007/09/17 09:15 AM
                  Coherency: Forwarding and OwnedPeter Gerdes2007/09/17 12:44 PM
  New article - The Common System Interface: Intel's Future InterconnectMr. Camel2007/08/30 03:16 PM
    New article - The Common System Interface: Intel's Future InterconnectMichael S2007/08/31 01:11 AM
      New article - The Common System Interface: Intel's Future InterconnectMr. Camel2007/08/31 03:13 AM
        New article - The Common System Interface: Intel's Future InterconnectMichael S2007/08/31 03:24 AM
        New article - The Common System Interface: Intel's Future InterconnectDavid Kanter2007/08/31 05:39 AM
          New article - The Common System Interface: Intel's Future InterconnectMichael S2007/08/31 06:53 AM
      New article - The Common System Interface: Intel's Future InterconnectDavid Kanter2007/08/31 05:41 AM
        New article - The Common System Interface: Intel's Future InterconnectMichael S2007/08/31 06:36 AM
          New article - The Common System Interface: Intel's Future InterconnectMr. Camel2007/08/31 08:36 AM
  Thanks and excellent work!Jack A.2007/08/30 07:41 PM
  Lamport's TLAKonrad Schwarz2007/09/02 01:57 AM
    Lamport's TLADavid Kanter2007/09/02 07:55 PM
    Lamport's TLABrannon2007/09/03 07:12 AM
      Lamport's TLAKonrad Schwarz2007/09/18 10:21 AM
        Lamport's TLABrannon2007/09/18 01:58 PM
  New article - The Common System Interface: Intel's Future InterconnectJosé Javier Zarate2007/09/09 04:01 PM
  New article - The Common System Interface: Intel's Future InterconnectJonathan Kang2007/09/16 05:42 PM
    Remote prefetchDavid Kanter2007/09/17 07:51 AM
  New article - The Common System Interface: Intel's Future InterconnectJigal2007/09/22 02:39 PM
    New article - The Common System Interface: Intel's Future InterconnectDavid Kanter2007/09/22 04:35 PM
      New article - The Common System Interface: Intel's Future Interconnect8B/10B Latency2007/09/22 06:16 PM
        New article - The Common System Interface: Intel's Future Interconnectanon2007/09/22 08:05 PM
          New article - The Common System Interface: Intel's Future InterconnectDavid W. Hess2007/09/22 08:50 PM
            Clocking in CSIDavid Kanter2007/09/23 08:46 AM
              Hypertransport 3 AC CouplingDavid W. Hess2007/09/23 09:32 AM
                Hypertransport 3 AC Couplinganon2007/09/23 09:53 AM
                  Clocking lanesDavid Kanter2007/09/23 10:51 AM
        New article - The Common System Interface: Intel's Future InterconnectDavid Kanter2007/09/22 08:34 PM
          New article - The Common System Interface: Intel's Future InterconnectDavid W. Hess2007/09/22 09:10 PM
            New article - The Common System Interface: Intel's Future InterconnectJonathan Kang2007/09/25 07:15 AM
          New article - The Common System Interface: Intel's Future InterconnectMichael S2007/09/23 01:06 AM
            New article - The Common System Interface: Intel's Future InterconnectDavid W. Hess2007/09/23 03:41 AM
            Serialization delayDavid Kanter2007/09/23 08:57 AM
              Serialization delayMichael S2007/09/23 11:20 AM
                Serialization delayDavid Kanter2007/09/23 12:43 PM
                  Serialization delayMichael S2007/09/24 12:40 AM
                    Serialization delayMichael S2007/09/24 04:28 AM
                    Serialization delayAaron Spink2007/09/24 12:19 PM
                      Serialization delayMichael S2007/09/25 03:38 AM
                        Serialization delayJonathan Kang2007/09/25 08:10 AM
                          Serialization delayDavid W. Hess2007/09/26 12:22 AM
                        Serialization delayAaron Spink2007/09/25 12:13 PM
                          Thank you (NT)Michael S2007/09/25 12:53 PM
                Serialization delayJonathan Kang2007/09/25 07:26 AM
                  Serialization delayMichael S2007/09/25 01:57 PM
                    Serialization delayJonathan Kang2007/09/26 05:24 AM
                      Serialization delayDavid W. Hess2007/09/26 06:39 AM
                        Serialization delayJonathan Kang2007/09/26 09:56 AM
                          Serialization delayDavid W. Hess2007/09/27 02:21 AM
                            Serialization delayJonathan Kang2007/09/27 04:36 AM
                              Serialization delayDavid W. Hess2007/09/27 05:31 PM
                      Serialization delayrwessel2007/09/26 01:26 PM
                        Serialization delayJonathan Kang2007/09/27 07:16 AM
                          Serialization delayrwessel2007/09/27 12:20 PM
                            Serialization delayJonathan Kang2007/09/28 04:38 AM
                              Serialization delayrwessel2007/09/28 01:00 PM
                                Serialization delayJonathan Kang2007/10/01 07:07 AM
                                  Cache coherent latencyDavid Kanter2007/10/01 07:20 AM
                                    Cache coherent latencyblaine2007/10/01 10:36 AM
                                      Critical word first on coherent interconnectsDavid Kanter2007/10/01 11:10 AM
                                        Does ccHT do critical word first?blaine2007/10/02 07:10 AM
                                    Cache coherent latencyJonathan Kang2007/10/01 12:34 PM
                                      Cache coherent latencyDavid Kanter2007/10/01 01:13 PM
                      Serialization delayMichael S2007/09/28 04:32 AM
                        Serialization delayanonymous2007/09/28 10:25 AM
                          Serialization delayMichael S2007/09/29 09:06 AM
        New article - The Common System Interface: Intel's Future InterconnectJonathan Kang2007/09/25 07:05 AM
      New article - The Common System Interface: Intel's Future Interconnectjigal2007/09/23 12:37 PM
        CSI, PCI and HTDavid Kanter2007/09/23 12:46 PM
        New article - The Common System Interface: Intel's Future InterconnectJonathan Kang2007/09/25 07:39 AM
          New article - The Common System Interface: Intel's Future Interconnectjigal2007/09/25 02:16 PM
            New article - The Common System Interface: Intel's Future InterconnectMichael S2007/09/26 03:14 AM
              New article - The Common System Interface: Intel's Future InterconnectAnonymous2007/09/26 09:41 AM
                New article - The Common System Interface: Intel's Future InterconnectJonathan Kang2007/09/26 09:59 AM
            New article - The Common System Interface: Intel's Future InterconnectJonathan Kang2007/09/26 05:48 AM
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