Coherency: Forwarding and Owned

Article: The Common System Interface: Intel's Future Interconnect
By: Jonathan Kang (johnbk.delete@this.gmail.com), September 17, 2007 5:16 am
Room: Moderated Discussions
I'm not too familiar with how the cache-line write-back of modern x86's are done but it makes sense to use a write-back immediately scheme in the case where a cache-line is stored in a memory pool connected to a third chip.

So let's say MPU0 stores a cache-line of modified data (C0) that belongs to MPU2. MPU1 and MPU3 then requests the cache-line and gets C0. At this point, there'd have to be multiple states if MPU0 were to avoid a write-back (one for the state inside MPU2 and one for the state inside MPU0) in addition to another state for data stored in MPU1 and MPU3.

Firing off a write-back command to MPU2 will update its cache with the modified data (C0) but, depending no how write-back commands are handled, doesn't necessarily mean that a memory write will occur. It simply means that MPU2 will get new data along with MPU1 and MPU3. MPU0 can then mark the cache-line as written back and never worry about it. It's then MPU2's job (which is convenient since it is directly tied to the physical memory that stores it) to respond with ACK's when a snoop occurs.

This naturally creates a situation when dirty cache-lines are handled by the MPU that is connected to the physical memory.
< Previous Post in ThreadNext Post in Thread >
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
Reply to this Topic
Name:
Email:
Topic:
Body: No Text
How do you spell avocado?