Example of memory ordering causing excitement in the real world

By: Gabriele Svelto (gabriele.svelto.delete@this.gmail.com), July 21, 2015 12:46 pm
Room: Moderated Discussions
anon (anon.delete@this.anon.com) on July 21, 2015 8:17 am wrote:
> That would still be interesting to know of. I do recall a long ago conversation with an IBM guy who worked
> on POWER implementation talking about implementation of one of their barriers (sync, or perhaps eieio)
> being improved such that it no longer had to go to fabric, somewhere around POWER4 to POWER5 transition.

POWER4 does stores in strict program order to the coherency point so lwsync instructions are effectively no-ops when preceding a store (all stores are store-release already) and must prevent loads from being reordered ahead of a preceding load to make it a load-acquire. Maybe is you were thinking about it? I thought about it because lwsync was introduced with the POWER4 possibly to leverage this implementation detail which makes it a vastly cheaper instruction than the heavyweight sync/isync and definitely doesn't need to do anything outside of a core.
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                    Example of memory ordering causing excitement in the real worldMark Roulo2015/07/08 04:54 PM
                      Example of memory ordering causing excitement in the real worlddmcq2015/07/09 04:37 AM
                        Example of memory ordering causing excitement in the real worldMark Roulo2015/07/09 08:24 AM
                          Example of memory ordering causing excitement in the real worlddmcq2015/07/09 10:09 AM
                          Example of memory ordering causing excitement in the real worldMaynard Handley2015/07/09 10:12 AM
                            Example of memory ordering causing excitement in the real worldLinus Torvalds2015/07/09 12:14 PM
                              Example of memory ordering causing excitement in the real worlddmcq2015/07/09 04:24 PM
                                Example of memory ordering causing excitement in the real worldSimon Farnsworth2015/07/10 01:07 PM
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                                        Example of memory ordering causing excitement in the real worldMichael S2015/07/13 05:19 AM
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                                          Example of memory ordering causing excitement in the real worlddmcq2015/07/14 02:54 PM
                                            Example of memory ordering causing excitement in the real worldSimon Farnsworth2015/07/15 01:13 PM
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                                                  Example of memory ordering causing excitement in the real worldWilco2015/07/17 01:57 PM
                                                    Example of memory ordering causing excitement in the real worldLinus Torvalds2015/07/17 04:29 PM
                                                      Example of memory ordering causing excitement in the real worlddmcq2015/07/18 04:07 AM
                                          Example of memory ordering causing excitement in the real worldJouni Osmala2015/07/16 03:52 AM
                                            Example of memory ordering causing excitement in the real worldSimon Farnsworth2015/07/16 01:05 PM
                                              Example of memory ordering causing excitement in the real worldJouni Osmala2015/07/17 01:18 AM
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                                  Example of memory ordering causing excitement in the real worldanon2015/07/12 03:42 AM
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                                    Example of memory ordering causing excitement in the real worldLinus Torvalds2015/07/12 11:24 AM
                                      Example of memory ordering causing excitement in the real worldEduardoS2015/07/12 11:53 AM
                                        Example of memory ordering causing excitement in the real worldLinus Torvalds2015/07/12 01:07 PM
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                                              Example of memory ordering causing excitement in the real worlddmcq2015/07/13 12:20 PM
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                                                    Example of memory ordering causing excitement in the real worldEtienne2015/07/17 01:15 AM
                                                  Example of memory ordering causing excitement in the real worlddmcq2015/07/13 02:14 PM
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                                                  Example of memory ordering causing excitement in the real worlddmcq2015/07/13 03:24 PM
                                                    Example of memory ordering causing excitement in the real worldEduardoS2015/07/13 04:48 PM
                                                      Example of memory ordering causing excitement in the real worldMaynard Handley2015/07/13 07:18 PM
                                                        Example of memory ordering causing excitement in the real worldEduardoS2015/07/13 07:57 PM
                                                      Example of memory ordering causing excitement in the real worldanon2015/07/13 09:01 PM
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                                                  Example of memory ordering causing excitement in the real worldWilco2015/07/13 04:36 PM
                                                    Example of memory ordering causing excitement in the real worldEduardoS2015/07/13 04:56 PM
                                                      Example of memory ordering causing excitement in the real worldanon2015/07/13 06:43 PM
                                                        Example of memory ordering causing excitement in the real worldEduardoS2015/07/13 08:11 PM
                                                          Example of memory ordering causing excitement in the real worldanon2015/07/13 09:07 PM
                                      Example of memory ordering causing excitement in the real worldMaynard Handley2015/07/12 12:32 PM
                                        Example of memory ordering causing excitement in the real worldEduardoS2015/07/12 01:35 PM
                                        Example of memory ordering causing excitement in the real worldLinus Torvalds2015/07/12 01:38 PM
                                          Example of memory ordering causing excitement in the real worldEduardoS2015/07/12 06:47 PM
                                            Example of memory ordering causing excitement in the real worldNoSpammer2015/07/13 12:34 PM
                                              Example of memory ordering causing excitement in the real worldWilco2015/07/13 04:50 PM
                                                Example of memory ordering causing excitement in the real worldNoSpammer2015/07/14 02:02 PM
                                                  Example of memory ordering causing excitement in the real worldanon2015/07/14 09:37 PM
                                                    Example of memory ordering causing excitement in the real worldMichael S2015/07/15 01:19 AM
                                                      Example of memory ordering causing excitement in the real worldanon2015/07/15 02:26 AM
                                                        Example of memory ordering causing excitement in the real worldNoSpammer2015/07/15 07:05 AM
                                                          Example of memory ordering causing excitement in the real worlddmcq2015/07/15 08:04 AM
                                                            Example of memory ordering causing excitement in the real worldMichael S2015/07/15 08:29 AM
                                                              Example of memory ordering causing excitement in the real worlddmcq2015/07/15 10:09 AM
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                                                            Example of memory ordering causing excitement in the real worldNoSpammer2015/07/15 12:50 PM
                                                              Example of memory ordering causing excitement in the real worldLinus Torvalds2015/07/15 02:27 PM
                                                                Example of memory ordering causing excitement in the real worldNoSpammer2015/07/15 03:14 PM
                                                                  Example of memory ordering causing excitement in the real worldLinus Torvalds2015/07/15 05:42 PM
                                                      Example of memory ordering causing excitement in the real worldNoSpammer2015/07/15 02:44 AM
                                                    Example of memory ordering causing excitement in the real worldLinus Torvalds2015/07/15 02:17 PM
                                                      Example of memory ordering causing excitement in the real worldWilco2015/07/15 02:43 PM
                                                        Example of memory ordering causing excitement in the real worldanon2015/07/15 05:45 PM
                                                        Example of memory ordering causing excitement in the real worldLinus Torvalds2015/07/15 06:35 PM
                                                          Example of memory ordering causing excitement in the real worlddmcq2015/07/16 02:46 AM
                                                            Example of memory ordering causing excitement in the real worlddmcq2015/07/16 02:49 AM
                                        Example of memory ordering causing excitement in the real worldKonrad Schwarz2015/07/21 07:15 AM
                                      Example of memory ordering causing excitement in the real worldanon2015/07/12 07:42 PM
                                        Example of memory ordering causing excitement in the real worldanon2015/07/12 09:48 PM
                                        Example of memory ordering causing excitement in the real worldDavid Kanter2015/07/12 10:34 PM
                                          Example of memory ordering causing excitement in the real worldMichael S2015/07/13 01:51 AM
                                            Example of memory ordering causing excitement in the real worldDavid Kanter2015/07/13 08:31 AM
                                          Example of memory ordering causing excitement in the real worldanon2015/07/13 06:05 AM
                                            Example of memory ordering causing excitement in the real worldGabriele Svelto2015/07/17 05:40 AM
                                          Example of memory ordering causing excitement in the real worlddmcq2015/07/13 08:09 AM
                                        Example of memory ordering causing excitement in the real worldanon2015/07/13 07:46 AM
                                          Example of memory ordering causing excitement in the real worldanon2015/07/14 04:12 AM
                                        Example of memory ordering causing excitement in the real worlddmcq2015/07/15 03:51 AM
                                          Example of memory ordering causing excitement in the real worldanon2015/07/15 04:38 AM
                                            Example of memory ordering causing excitement in the real worlddmcq2015/07/15 06:21 AM
                                      Store queues in POWER/PowerPC processorsGabriele Svelto2015/07/16 01:55 AM
                                        Not sure about that conclusionDavid Kanter2015/07/16 07:34 AM
                                          The POWER4 had the same structureGabriele Svelto2015/07/17 05:20 AM
                                        Committing stores in program orderPaul A. Clayton2015/07/16 01:35 PM
                                          Committing stores in program orderMaynard Handley2015/07/17 12:52 PM
                                      Example of memory ordering causing excitement in the real worldKonrad Schwarz2015/07/20 04:44 AM
                                        Example of memory ordering causing excitement in the real worldanon2015/07/20 07:29 AM
                                          Example of memory ordering causing excitement in the real worldKonrad Schwarz2015/07/21 12:08 AM
                                            Example of memory ordering causing excitement in the real worlddmcq2015/07/21 01:27 AM
                                            Example of memory ordering causing excitement in the real worldMichael S2015/07/21 03:11 AM
                                              Example of memory ordering causing excitement in the real worldKonrad Schwarz2015/07/21 05:24 AM
                                            Example of memory ordering causing excitement in the real worldanon2015/07/21 06:22 AM
                                              Example of memory ordering causing excitement in the real worldKonrad Schwarz2015/07/21 07:36 AM
                                                Example of memory ordering causing excitement in the real worldanon2015/07/21 08:25 AM
                                              Example of memory ordering causing excitement in the real worldanon2015/07/21 08:17 AM
                                                Example of memory ordering causing excitement in the real worldanon2015/07/21 09:50 AM
                                                Example of memory ordering causing excitement in the real worldGabriele Svelto2015/07/21 12:46 PM
                                                Example of memory ordering causing excitement in the real worldKonrad Schwarz2015/07/22 12:35 AM
                                                  Example of memory ordering causing excitement in the real worldKonrad Schwarz2015/07/22 01:37 AM
                                                  Example of memory ordering causing excitement in the real worldanon2015/07/23 03:17 AM
                                                    Example of memory ordering causing excitement in the real worldKonrad Schwarz2015/07/23 04:59 AM
                                                      Example of memory ordering causing excitement in the real worldMichael S2015/07/23 07:31 AM
                                                        Example of memory ordering causing excitement in the real worldKonrad Schwarz2015/07/23 03:38 PM
                                                          Example of memory ordering causing excitement in the real worldKonrad Schwarz2015/07/23 11:44 PM
                                                            Example of memory ordering causing excitement in the real worlddmcq2015/07/24 01:08 AM
                                    Example of memory ordering causing excitement in the real worlddmcq2015/07/13 07:27 AM
                          Example of memory ordering causing excitement in the real worldKonrad Schwarz2015/07/16 05:11 AM
                      Example of memory ordering causing excitement in the real worldAnonymousse2015/07/16 05:07 AM
          Benefit of dynamic hammock predicationsomeotherdude2015/07/06 05:12 PM
            Benefit of dynamic hammock predicationMichael S2015/07/07 01:19 AM
          Benefit of dynamic hammock predicationPatrick Chase2015/07/06 10:20 PM
            SIMD predication is also helpful, of course (NT)Paul A. Clayton2015/07/07 07:45 AM
        Power8 branch conversionGabriele Svelto2015/07/07 02:50 AM
          isel works for storesPaul A. Clayton2015/07/07 07:43 AM
            isel works for storesPatrick Chase2015/07/07 11:08 AM
            isel DOES NOT work for storessomeotherdude2015/07/07 04:01 PM
              isel DOES NOT work for storesWilco2015/07/07 04:40 PM
              Yes it doesPatrick Chase2015/07/07 11:14 PM
                Yes it doesvvid2015/07/08 09:51 AM
            You don't need isel eitherGabriele Svelto2015/07/08 02:01 AM
              You don't need isel eitherPaul A. Clayton2015/07/08 04:46 AM
                You don't need isel eitherGabriele Svelto2015/07/08 05:22 AM
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