Virtually tagged L1-caches

By: sr (nobody.delete@this.nowhere.com), September 11, 2021 1:19 am
Room: Moderated Discussions
--- (---.delete@this.redheron.com) on September 8, 2021 2:28 pm wrote:

> The claim that a highly performant TLB must be multi-ported is a myth.
> The theory is explained here: https://eprints.soton.ac.uk/347147/1/__userfiles.soton.ac.uk_Users_spd
> _mydesktop _MALEC.pdf
>
> The essential insight is that
> - most memory requests are strongly clustered to a single page or a few pages
> - to the extent that requests are spread over many pages, that same code
> is probably not exactly latency essential to the single cycle level


Many people still believes that L1-caches are VIPT. And if you support VIPT with single-ported TLB there will be performance penalties, VIPT is designed to support TLB result simultaneously with physical tag read to allow physical tag comparison. Doing VIPT wiht single-ported TLB would result increased cache latencies when accessed are split to different pages - and consequence is reduced bandwith too. I'm pretty sure that no high performance cpu design will suffers from that kind of performance problems.

And if you want to increase your CPU's performance per watt you should not do unnecessarily work. Doing address conversion for L1 hit validation isn't sane thing to do if it can be avoided. And it can.
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TopicPosted ByDate
POWER10 SAP SD benchmarkanon22021/09/06 03:36 PM
  POWER10 SAP SD benchmarkDaniel B2021/09/07 02:31 AM
    "Cores" (and SPEC)Rayla2021/09/07 07:51 AM
      "Cores" (and SPEC)anon2021/09/07 03:56 PM
  POWER10 SAP SD benchmarkAnon2021/09/07 03:24 PM
    POWER10 SAP SD benchmarkAnon2021/09/07 03:27 PM
  Virtually tagged L1-cachessr2021/09/08 05:49 AM
    Virtually tagged L1-cachesdmcq2021/09/08 08:22 AM
      Virtually tagged L1-cachessr2021/09/08 08:56 AM
      Virtually tagged L1-cachesHugo Décharnes2021/09/08 08:58 AM
        Virtually tagged L1-cachessr2021/09/08 10:09 AM
          Virtually tagged L1-cachesHugo Décharnes2021/09/08 10:46 AM
            Virtually tagged L1-cachessr2021/09/08 11:35 AM
              Virtually tagged L1-cachesHugo Décharnes2021/09/08 12:23 PM
                Virtually tagged L1-cachessr2021/09/08 12:40 PM
                  Virtually tagged L1-cachesanon2021/09/09 03:16 AM
                    Virtually tagged L1-cachesKonrad Schwarz2021/09/10 05:19 AM
                      Virtually tagged L1-cachesHugo Décharnes2021/09/10 06:59 AM
                        Virtually tagged L1-cachesanon2021/09/14 03:17 AM
                          Virtually tagged L1-cachesdmcq2021/09/14 09:34 AM
                            Or use a PLB (NT)Paul A. Clayton2021/09/14 09:45 AM
                              Or use a PLBLinus Torvalds2021/09/14 03:27 PM
                                Or use a PLBanon2021/09/15 12:15 AM
                                  Or use a PLBMichael S2021/09/15 03:21 AM
                                    Or use a PLBdmcq2021/09/15 03:42 PM
                                      Or use a PLBKonrad Schwarz2021/09/16 04:24 AM
                                        Or use a PLBMichael S2021/09/16 10:13 AM
                                          Or use a PLB---2021/09/16 01:02 PM
                                  PLB referencePaul A. Clayton2021/09/18 02:35 PM
                                    PLB referenceMichael S2021/09/18 04:14 PM
                                      Demand paging/translation orthogonalPaul A. Clayton2021/09/19 07:33 AM
                                        Demand paging/translation orthogonalMichael S2021/09/19 09:10 AM
                                      PLB referenceCarson2021/09/20 10:19 PM
                                    PLB referencesr2021/09/20 06:02 AM
                                      PLB referenceMichael S2021/09/20 07:03 AM
                                        PLB referenceLinus Torvalds2021/09/20 12:10 PM
                                  Or use a PLBsr2021/09/20 04:32 AM
                              Or use a PLBsr2021/09/21 09:36 AM
                                Or use a PLBLinus Torvalds2021/09/21 10:04 AM
                                  Or use a PLBsr2021/09/21 10:48 AM
                                    Or use a PLBLinus Torvalds2021/09/21 01:55 PM
                                      Or use a PLBsr2021/09/22 06:55 AM
                                        Or use a PLBrwessel2021/09/22 07:09 AM
                                        Or use a PLBLinus Torvalds2021/09/22 11:50 AM
                                          Or use a PLBsr2021/09/22 01:00 PM
                                            Or use a PLBdmcq2021/09/22 04:07 PM
                                            Or use a PLBEtienne Lorrain2021/09/23 08:50 AM
                                          Or use a PLBanon22021/09/22 04:09 PM
                                            Or use a PLBdmcq2021/09/23 02:35 AM
                                          Or use a PLB2021/09/23 09:37 AM
                                            Or use a PLBLinus Torvalds2021/09/23 12:01 PM
                                              Or use a PLBgpd2021/09/24 03:59 AM
                                                Or use a PLBLinus Torvalds2021/09/24 10:45 AM
                                                  Or use a PLBdmcq2021/09/24 12:43 PM
                                                  Or use a PLBsr2021/09/25 10:19 AM
                                                    Or use a PLBLinus Torvalds2021/09/25 10:44 AM
                                                      Or use a PLBsr2021/09/25 11:11 AM
                                                        Or use a PLBLinus Torvalds2021/09/25 11:31 AM
                                                          Or use a PLBsr2021/09/25 11:52 AM
                                                            Or use a PLBLinus Torvalds2021/09/25 12:05 PM
                                                              Or use a PLBsr2021/09/25 12:23 PM
                                                                Or use a PLBrwessel2021/09/25 03:29 PM
                                                                  Or use a PLBsr2021/10/01 12:22 AM
                                                                    Or use a PLBrwessel2021/10/01 06:19 AM
                                                                      Or use a PLBDavid Hess2021/10/01 10:35 AM
                                                                        Or use a PLBrwessel2021/10/02 04:47 AM
                                                                      Or use a PLBsr2021/10/02 11:16 AM
                                                                        Or use a PLBrwessel2021/10/02 11:53 AM
                                                          Or use a PLBLinus Torvalds2021/09/25 11:57 AM
                                                            Or use a PLBsr2021/09/25 12:07 PM
                                                              Or use a PLBLinus Torvalds2021/09/25 12:21 PM
                                                                Or use a PLBsr2021/09/25 12:40 PM
                                                                  Or use a PLBnksingh2021/09/27 09:07 AM
                                                          Or use a PLB2021/09/27 09:02 AM
                                                            Or use a PLBLinus Torvalds2021/09/27 10:20 AM
                                                              Or use a PLBLinus Torvalds2021/09/27 12:58 PM
                                                                Or use a PLBdmcq2021/09/28 10:59 AM
                                              Or use a PLBsr2021/09/25 10:34 AM
                                                Or use a PLBrwessel2021/09/25 03:44 PM
                                                  Or use a PLBsr2021/10/01 01:04 AM
                                                    Or use a PLBrwessel2021/10/01 06:33 AM
                                                      I386 segmentation highlightssr2021/10/04 07:53 AM
                                                        I386 segmentation highlightsAdrian2021/10/04 09:53 AM
                                                          I386 segmentation highlightssr2021/10/04 10:19 AM
                                                        I386 segmentation highlightsrwessel2021/10/04 04:57 PM
                                                          I386 segmentation highlightssr2021/10/05 11:16 AM
                                                            I386 segmentation highlightsMichael S2021/10/05 12:27 PM
                                                            I386 segmentation highlightsrwessel2021/10/05 04:20 PM
                                                Or use a PLBJohnG2021/09/25 10:18 PM
                                              Or use a PLB2021/09/27 07:37 AM
                                                Or use a PLBHeikki Kultala2021/09/28 03:53 AM
                                                  Or use a PLBrwessel2021/09/28 07:29 AM
                                        Or use a PLBDavid Hess2021/09/23 06:00 PM
                                          Or use a PLBAdrian2021/09/24 01:21 AM
                                            Or use a PLBdmcq2021/09/25 12:41 PM
                                        Or use a PLBblaine2021/09/26 11:19 PM
                                          Or use a PLBDavid Hess2021/09/27 11:35 AM
                                            Or use a PLBblaine2021/09/27 05:19 PM
                                            Or use a PLBAdrian2021/09/27 10:40 PM
                                              Or use a PLBAdrian2021/09/27 10:59 PM
                                                Or use a PLBdmcq2021/09/28 07:45 AM
                                              Or use a PLBrwessel2021/09/28 07:45 AM
                                              Or use a PLBDavid Hess2021/09/28 12:50 PM
                                                Or use a PLBEtienne Lorrain2021/09/30 01:25 AM
                                                  Or use a PLBDavid Hess2021/10/01 10:40 AM
                                  MMU privilegessr2021/09/21 11:07 AM
                                    MMU privilegesLinus Torvalds2021/09/21 01:49 PM
                            Virtually tagged L1-cachesKonrad Schwarz2021/09/16 04:18 AM
                          Virtually tagged L1-cachesCarson2021/09/16 01:12 PM
                            Virtually tagged L1-cachesanon22021/09/16 05:16 PM
                              Virtually tagged L1-cachesrwessel2021/09/16 06:29 PM
                          Virtually tagged L1-cachessr2021/09/20 04:20 AM
              Virtually tagged L1-caches---2021/09/08 02:28 PM
                Virtually tagged L1-cachesanonymou52021/09/08 08:28 PM
                  Virtually tagged L1-cachesanonymou52021/09/08 08:34 PM
                  Virtually tagged L1-caches---2021/09/09 10:14 AM
                    Virtually tagged L1-cachesanonymou52021/09/09 10:44 PM
                Multi-threading?David Kanter2021/09/09 09:32 PM
                  Multi-threading?---2021/09/10 09:19 AM
                Virtually tagged L1-cachessr2021/09/11 01:19 AM
                Virtually tagged L1-cachessr2021/09/11 01:36 AM
                  Virtually tagged L1-caches---2021/09/11 09:53 AM
                    Virtually tagged L1-cachessr2021/09/12 12:43 AM
                      Virtually tagged L1-cachesLinus Torvalds2021/09/12 11:10 AM
                        Virtually tagged L1-cachessr2021/09/12 11:57 AM
                          Virtually tagged L1-cachesdmcq2021/09/13 08:31 AM
                            Virtually tagged L1-cachessr2021/09/20 04:11 AM
            Virtually tagged L1-cachessr2021/09/11 02:49 AM
      Virtually tagged L1-cachesLinus Torvalds2021/09/08 12:34 PM
        Virtually tagged L1-cachesdmcq2021/09/09 02:46 AM
          Virtually tagged L1-cachesdmcq2021/09/09 02:58 AM
          Virtually tagged L1-cachessr2021/09/11 01:29 AM
            Virtually tagged L1-cachesdmcq2021/09/11 08:59 AM
              Virtually tagged L1-cachessr2021/09/12 12:57 AM
                Virtually tagged L1-cachesdmcq2021/09/12 08:44 AM
                  Virtually tagged L1-cachessr2021/09/12 09:48 AM
                    Virtually tagged L1-cachesdmcq2021/09/12 01:22 PM
                      Virtually tagged L1-cachessr2021/09/20 04:40 AM
    Where do you see this information? (NT)anon22021/09/09 02:45 AM
      Where do you see this information?sr2021/09/11 01:40 AM
        Where do you see this information?anon22021/09/11 01:53 AM
          Where do you see this information?sr2021/09/11 02:08 AM
            Thank you (NT)anon22021/09/11 04:31 PM
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