In defense of Bulldozer's Oddities

By: hcl64 (mario.smarq.delete@this.gmail.com), April 28, 2012 2:44 pm
Room: Moderated Discussions
David Kanter (dkanter@realworldtech.com) on 4/28/12 wrote:
---------------------------
>hcl64 (mario.smarq@gmail.com) on 4/27/12 wrote:
>---------------------------
>>David Kanter (dkanter@realworldtech.com) on 4/20/12 wrote:
>>---------------------------
>>>
>>>You are correct that the caches are painfully slow, but that's not the reason why.
>>>Frankly, I don't understand why the L1 is 4 cycles instead of 3. I REALLY don't
>>>understand why the L2 cache is so slow (20 cycles, really??), because size alone
>>>doesn't account for it. 12-14 cycles sounds much more reasonable.
>>>
>>>The L3 cache is also quite slow, in part because of the slow L2 and in part because
>>>it runs at asynchronous to the cores. If you look at those two factors together
>>>and assume a 14 cycle L2, you can probably cut the L3 latency down by ~10 cycles.
>>>
>>>
>>>DK
>
>>Good points. But isn't BD mostly asynchronous or semi->synchronous ?
>
>No. You should read my article about Bulldozer.
>
>http://www.realworldtech.com/page.cfm?ArticleID=RWT082610181333
>
>Decoupled and asynchronous mean very different things. Asynchronous refers to frequency.
>Decoupled means there are buffers between stages. Those are two very different
>concepts and have very different implications for design.
>
>DK

Well its a point, but it fits my understanding of "asynchronous"... if as example, the "decode domain" is crunching thread A, which is stalled at core0 in the "execution domain", but the core1 is executing thread B at the same exec domain... then the "decode domain" and the "exec domain" are asynchronous. And the same can be said for most other domains, "Decode" at thread A and "Dispatch" at thread B as example

http://en.wikipedia.org/wiki/Asynchrony

" In specific terms of digital logic and physical layer of communication, an *asynchronous process does not require a clock signal*, in contrast with synchronous and plesiochronous systems."

"At the higher data link layer of communication, asynchrony is synonym of statistical multiplexing, such as in packet mode. The information transmission may or may not start immediately as requested by sender, the additional delay being caused by medium congestion. Contrast with example of circuit switched communication, which (once circuit is established) allows immediate start of transfer with a guaranteed bit rate. Confusingly, a communication is often synchronous at the physical layer, while being asynchronous at the data link layer."

**" In programming, asynchronous events are those occurring independently of the main program flow. Asynchronous actions are actions executed in a non-blocking scheme, allowing the main program flow to continue processing."**
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                Bulldozer's Oddities.Joel2012/04/20 04:54 PM
                  In defense of Bulldozer's OdditiesDavid Kanter2012/04/20 05:32 PM
                    In defense of Bulldozer's OdditiesExophase2012/04/20 07:11 PM
                      In defense of Bulldozer's OdditiesEduardoS2012/04/20 07:46 PM
                        In defense of Bulldozer's OdditiesExophase2012/04/20 08:18 PM
                          In defense of Bulldozer's Odditiesanonymous2012/04/20 11:26 PM
                            In defense of Bulldozer's OdditiesJJB2012/04/20 11:34 PM
                              In defense of Bulldozer's Odditiesimaxx2012/04/21 07:21 AM
                                In defense of Bulldozer's OdditiesMichael S2012/04/21 10:42 AM
                                  Bulldozer's integer execution unitsDavid Kanter2012/04/25 04:29 PM
                                    Bulldozer's integer execution unitsExophase2012/04/26 12:17 PM
                                      Bulldozer's integer execution unitsanonymous2012/04/26 03:15 PM
                                        Bulldozer's integer execution unitsEduardoS2012/04/26 03:40 PM
                                          Bulldozer's integer execution unitsFoo_2012/04/27 08:21 AM
                                            Bulldozer's integer execution unitsMegol2012/04/27 01:38 PM
                                      Bulldozer's integer execution unitsEduardoS2012/04/26 03:47 PM
                                        Bulldozer's integer execution unitsExophase2012/04/26 05:02 PM
                                          Bulldozer's integer execution unitsEduardoS2012/04/26 06:03 PM
                                            Bulldozer's integer execution unitsExophase2012/04/26 06:24 PM
                                              Bulldozer's integer execution unitsEduardoS2012/04/26 07:18 PM
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                                                  Bulldozer's cache memory performanceEduardoS2012/04/28 10:06 AM
                                      Bulldozer's integer execution unitsDavid Kanter2012/04/26 04:03 PM
                                        Bulldozer's integer execution unitsExophase2012/04/26 04:59 PM
                                          Bulldozer's integer execution unitsDavid Kanter2012/04/26 10:53 PM
                                            Bulldozer's integer execution unitsExophase2012/04/27 08:42 AM
                                              Bulldozer's integer execution unitsDavid Kanter2012/04/27 11:06 AM
                                                Bulldozer's integer execution unitsEduardoS2012/04/27 01:27 PM
                                                K8 divided pipelines?Paul A. Clayton2012/04/27 01:59 PM
                                          Bulldozer's integer execution unitsMichael S2012/04/27 04:37 AM
                                            Bulldozer's integer execution unitsExophase2012/04/27 08:33 AM
                                            Bulldozer's integer execution unitsanonymous2012/04/27 09:03 AM
                                    Renaming FlagsKonrad Schwarz2012/04/27 03:04 AM
                                      Renaming Flagsnone2012/04/27 04:03 AM
                                        Renaming FlagsMegol2012/04/27 12:42 PM
                                    Bulldozer's integer execution unitshcl642012/04/27 04:31 PM
                                      VEX supports 3+ operands. FPU have renaming already(NT)Megol2012/04/28 08:20 AM
                              In defense of Bulldozer's OdditiesLinus Torvalds2012/04/21 12:26 PM
                                Thanks for the lessonJJB2012/04/21 02:23 PM
                                  Side note..Linus Torvalds2012/04/21 02:57 PM
                            In defense of Bulldozer's OdditiesExophase2012/04/21 12:13 PM
                            In defense of Bulldozer's OdditiesEduardoS2012/04/21 12:53 PM
                    In defense of Bulldozer's OdditiesGionatan Danti2012/04/21 12:42 PM
                    In defense of Bulldozer's Odditieshcl642012/04/27 05:07 PM
                      In defense of Bulldozer's OdditiesDavid Kanter2012/04/28 06:29 AM
                        In defense of Bulldozer's Odditieshcl642012/04/28 02:44 PM
                          In defense of Bulldozer's OdditiesDavid Kanter2012/04/28 09:42 PM
                            In defense of Bulldozer's Odditieshcl642012/04/28 10:39 PM
                  Bulldozer's Oddities.EduardoS2012/04/20 06:05 PM
                    Bulldozer's Oddities.anon2012/04/20 08:32 PM
                      Bulldozer's Oddities.EduardoS2012/04/21 12:37 PM
                        Bulldozer's Oddities.anon2012/04/21 10:16 PM
                          Bulldozer's Oddities.EduardoS2012/04/21 10:43 PM
                            Bulldozer's Oddities.anon2012/04/22 02:09 AM
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                                Bulldozer's Oddities.anon2012/04/22 04:17 PM
                                  Bulldozer's Oddities.EduardoS2012/04/22 05:05 PM
                                    Bulldozer's Oddities.anon2012/04/22 05:42 PM
                                      Bulldozer's Oddities.anon2012/04/22 06:01 PM
                                      Bulldozer's Oddities.EduardoS2012/04/22 10:28 PM
                                        Bulldozer's Oddities.anon2012/04/22 11:05 PM
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                      Bulldozer's isn't bad.hcl642012/04/27 05:58 PM
                        Bulldozer's isn't bad.anon2012/04/27 06:16 PM
                          Bulldozer's isn't bad.hcl642012/04/27 07:33 PM
                            Bulldozer's isn't bad.rwessel2012/04/27 11:12 PM
                        Bulldozer's isn't bad.EduardoS2012/04/28 09:29 AM
                          Bulldozer's isn't bad.EduardoS2012/04/28 09:30 AM
                          Bulldozer's isn't bad.Michael S2012/04/28 12:36 PM
                    Bulldozer is made for SPEC fpPelle-482012/04/21 11:41 AM
                  Bulldozer's Oddities.mpx2012/04/22 03:47 AM
                    Bulldozer's Oddities.EduardoS2012/04/22 01:57 PM
                      Bulldozer's Oddities.mpx2012/04/23 07:04 AM
                        Bulldozer's Oddities.Eric2012/04/23 12:33 PM
                          Bulldozer's Oddities.EduardoS2012/04/23 02:22 PM
                            Bulldozer's Oddities.Eric2012/04/23 07:30 PM
                              Bulldozer's Oddities.hcl642012/04/27 06:16 PM
                            Bulldozer's Oddities.Y2012/04/25 04:34 AM
                              Bulldozer's IDIVHeikki Kultala2012/04/27 10:56 PM
                                Bulldozer's IDIVY2012/04/30 01:51 AM
                                  Bulldozer's IDIVEduardoS2012/04/30 05:39 AM
                                    Bulldozer's IDIVP3Dnow2012/05/08 01:23 AM
                                      Bulldozer's IDIVExophase2012/05/08 07:37 AM
                        Bulldozer's Oddities.EduardoS2012/04/23 02:15 PM
              Clustered MT as SMT for high frequencyPaul A. Clayton2012/04/20 04:10 PM
                Clustered MT as SMT for high frequencyhcl642012/04/28 12:56 AM
                  Clustered MT as SMT for high frequencyanonymous2012/04/28 01:43 AM
                    Clustered MT as SMT for high frequencyhcl642012/04/28 02:59 PM
                      Clustered MT as SMT for high frequencyanonymous2012/04/28 08:45 PM
                  Clustered MT as SMT for high frequencyanon2012/04/28 02:13 AM
                    Clustered MT as SMT for high frequencyhcl642012/04/28 03:23 PM
                      Clustered MT as SMT for high frequencyanon2012/04/28 06:19 PM
                        Clustered MT as SMT for high frequencyhcl642012/04/28 07:58 PM
                  Clustered MT as SMT for high frequencyDavid Kanter2012/04/28 06:38 AM
                    Guessed meaning of "strong dependency model"Paul A. Clayton2012/04/28 07:24 AM
                      Guessed meaning of "strong dependency model"EduardoS2012/04/28 09:46 AM
                        *Right meaning* about "strong dependency model"hcl642012/04/28 04:59 PM
                    Clustered MT as SMT for high frequencyhcl642012/04/28 04:24 PM
                      Clustered MT as SMT for high frequencyanonymous2012/04/28 08:50 PM
                        Clustered MT as SMT for high frequencyhcl642012/04/28 09:47 PM
                          SNB widthDavid Kanter2012/04/28 09:48 PM
                            SNB widthhcl642012/04/29 02:24 AM
                      Clustered MT as SMT for high frequencyDavid Kanter2012/04/28 09:56 PM
                        Clustered MT as SMT for high frequencyhcl642012/04/28 11:44 PM
                          SOI, FD vs. PDDavid Kanter2012/04/29 07:19 AM
                            SOI, FD vs. PDhcl642012/04/29 05:31 PM
                              SOI, FD vs. PDDavid Kanter2012/04/29 11:26 PM
                                SOI, FD vs. PDhcl642012/04/30 08:08 AM
                                  SOI, FD vs. PDDavid Kanter2012/04/30 09:59 AM
                                    SOI, FD vs. PDhcl642012/04/30 06:10 PM
                                      SOI, FD vs. PDDavid Kanter2012/04/30 06:32 PM
                                        SOI, FD vs. PDhcl642012/04/30 10:47 PM
                                          SOI, FD vs. PDDavid Kanter2012/05/01 02:24 AM
                                            SOI, FD vs. PDhcl642012/05/01 05:46 AM
                                            SOI, FD vs. PDhcl642012/05/01 06:37 AM
                                              SOI, FD vs. PDDavid Kanter2012/05/01 08:19 AM
                                          SOI, FD vs. PDhcl642012/05/01 07:39 AM
                                            PD-SOIDavid Kanter2012/05/02 12:22 PM
                                    SOI, FD vs. PDslacker2012/04/30 08:10 PM
                                      SOI, FD vs. PDDavid Kanter2012/04/30 10:16 PM
                                        SOI, FD vs. PDslacker2012/05/01 10:04 PM
                                          SOI, FD vs. PDDavid Kanter2012/05/02 08:19 AM
                                            SOI, FD vs. PDzou2012/05/02 12:23 PM
                  Previous discussion of clustered MTPaul A. Clayton2012/04/28 07:00 AM
                    Previous discussion of clustered MThcl642012/04/28 09:38 PM
                      Previous discussion of clustered MTDavid Kanter2012/04/30 04:37 PM
                        Previous discussion of clustered MThcl642012/04/30 07:24 PM
                          Previous discussion of clustered MTDavid Kanter2012/04/30 07:40 PM
                            Previous discussion of clustered MThcl642012/05/01 09:15 AM
                              Latency issuesDavid Kanter2012/05/02 12:01 PM
              So, what do people think of these numbers>Megol2012/04/21 01:57 AM
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