Accurate branch prediction is not everything

By: Paul A. Clayton (paaronclayton.delete@this.gmail.com), June 14, 2022 11:48 am
Room: Moderated Discussions
--- (---.delete@this.redheron.com) on June 5, 2022 6:12 pm wrote:
> ⚛ (0xe2.0x9a.0x9b.delete@this.gmail.com) on June 4, 2022 11:39 am wrote:
> > Peter Lewis (peter.delete@this.notyahoo.com) on June 1, 2022 3:55 pm wrote:
>
> > It is possible that in the near future it will become clear that CPU performance is determined
> > by the number of [conditional] branches successfully predicted per cycle - and not by whether
> > the CPU's compiler/user interface uses a fixed-length or a variable-length encoding.
>
> This is a great point, a rare example of skating to where the
> puck will be rather than where it was thirty years ago.

While I would agree that variable- or fixed-length encoding is not as important correctly predicting branches (with the implication of greater memory level parallelism for both instructions and data), branch prediction accuracy is less important if "microtask" parallelism is abundant (i.e., accurate branch prediction discovers tasks that can be done by looking ahead in a single instruction flow but their independence is evaluated per instruction/operation). Even hardware-supported speculative multithreading could benefit from information available to the compiler. (Using execution and caching resources with higher communication latency from each other has costs and benefits which depend of the scale of the independence, nature of communication (stream, message passing, "random access", etc.), and other factors. Thermal density constraints discourage proximity, but local communication can reduce static/idle energy (low latency → low time to completion) and active energy. Currently, support for lower-cost sharing seems to be limited to L1 sharing for multithreaded cores and L2 or L3 sharing within a cluster of cores, though network hop distance is also a factor. [I think x86 has support for explicitly writing back dirty cache lines to shared cache, but this seems a crude mechanism.])

There is also the factor that not all branch mispredictions are equally expensive. Resolution delay is one factor; a branch misprediction resolved twelve cycles after prediction will typically be less expensive than one resolved fifty cycles after prediction. A processor might also be able to exploit value and instruction reuse after a mispredicted branch to reduce work and/or perform more work in parallel for execution of the corrected path. (This might be an aspect where software's broader perspective might be helpful.) Caching branch conditions has been proposed for loops, but a similar mechanism might be useful for early branch resolution in a retry; even merely predictions might be guided by information from the incorrectly speculated path (a similar method has been proposed for transactional memory retries: recording participants and prefetching them).

> As regards ISA, the obvious question, then, is what can ISA do to improve this situation?

[snip compiler use of predication and hardware dynamic hammock predication]

Communicating information about branch independence/dependence and perhaps correlation might be useful.

> - a dark horse is ARM's new (v8.8) Branch Consistent (BC) instruction. Does anyone know
> the backstory behind this (like is it from within ARM or an Apple suggestion or ???)
> It's somewhat vaguely described (and much may be in the hands of the implementer) but my simple-minded
> reading of it is that it's a way to move the easy branches (as always, assuming the compiler
> can get its act together...) out of the fancy branch machinery to much simpler branch machinery,
> so that the few really hard branches can have much more tech thrown at them.

In addition to potentially allowing trivially predicted branches to use fewer resources, this information might also be useful in managing global history. (Of course, a dynamic predictor could also detect that a branch is "consistent" and adjust global history.)

The definition of "consistent" is also not entirely clear to me. Is a branch with long phases of the same direction consistent? (Such a branch should not be statically predicted but a one-bit predictor would be accurate and trace-like optimizations could have better cost-benefit than for shorter-term variability in direction.)

(One could divide local-history-predictable branches into three extreme transition rate classes: high transition rate [predict opposite of last is accurate], low transistion rate [phased behavior, these are well-predicted by typical predictors], and direction-dependent transition rate [loop-like behavior has 100% transition rate for one direction — not-taken for backward loop branches — and typically a lower transition rate for the other direction, typical predictors 'ignore' the high transition rate direction]. Even awareness of the value of local history may be useful. [The alternative to saturating counter 2-bit predictors has the advantage of providing the previous direction as the hysteresis bit. This could be fed into a global predictor. Even the previous direction of spatially nearby branches might be more useful information than ordinary global history; if the "per-address" predictor could group temporally local branches, the information value density might be increased.])

Converting branch trees into indexed jumps (where the potential targets are encoded in the instruction stream/available early and the predictor predicts the index) may be useful. If the frequency of different indexes was not known at compile time, the branch tree might often have multiple mispredictions; a single index would have one misprediction. Even if the condition evaluations needed for producing an index involved significant work, (eagerly) generating one index might be more performant than (lazy) tree evaluation.
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TopicPosted ByDate
Apple's AVX512---2022/05/12 12:32 AM
  Apple's AVX512Rayla2022/05/12 08:23 AM
    Apple's AVX512---2022/05/12 10:49 AM
      Apple's AVX512---2022/05/12 10:59 AM
  Questions About Apple's AVX512Matt Lohmann2022/05/13 05:21 AM
    Questions About Apple's AVX512---2022/05/13 09:33 AM
      Questions About Apple's AVX512Doug S2022/05/13 10:22 AM
        Questions About Apple's AVX512---2022/05/13 02:05 PM
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            Questions About Apple's AVX512Anon12022/05/14 12:53 AM
            Questions About Apple's AVX512Simon Farnsworth2022/05/14 05:20 AM
              Questions About Apple's AVX512Michael S2022/05/14 12:27 PM
                Questions About Apple's AVX512Doug S2022/05/15 10:50 AM
                  Questions About Apple's AVX512Michael S2022/05/15 01:01 PM
                    Questions About Apple's AVX512Doug S2022/05/16 12:59 AM
                      Questions About Apple's AVX512Michael S2022/05/16 02:29 AM
                    what it takes to really vectorizeRichardC2022/05/16 02:47 PM
                  Questions About Apple's AVX512---2022/05/16 10:22 PM
                    Questions About Apple's AVX512rwessel2022/05/17 01:42 AM
                      Questions About Apple's AVX512anon12022/05/17 04:47 AM
                        Questions About Apple's AVX512Michael S2022/05/17 06:28 AM
                          Questions About Apple's AVX512anon12022/05/18 01:15 AM
                            Questions About Apple's AVX512-.-2022/05/18 03:41 AM
                              Questions About Apple's AVX512Jan Wassenberg2022/05/18 10:23 PM
                                Questions About Apple's AVX512-.-2022/05/19 06:11 AM
                                  Questions About Apple's AVX512Jan Wassenberg2022/05/19 06:45 AM
                                    Questions About Apple's AVX512-.-2022/05/20 04:04 AM
                                      Questions About Apple's AVX512Jan Wassenberg2022/05/20 10:00 PM
                Questions About Apple's AVX512anon12022/05/16 04:44 AM
              Questions About Apple's AVX512Jörn Engel2022/05/15 11:34 PM
                Questions About Apple's AVX512Simon Farnsworth2022/05/16 04:13 AM
                  Questions About Apple's AVX512Jörn Engel2022/05/16 12:52 PM
                    Backward Compatibility for SVE2 CodeCharlie Burnes2022/05/16 06:57 PM
                      Backward Compatibility for SVE2 CodeJörn Engel2022/05/17 12:30 AM
                        Backward Compatibility for SVE2 CodeCharlie Burnes2022/05/17 03:31 AM
                          Backward Compatibility for SVE2 CodeJörn Engel2022/05/17 10:24 AM
                            Backward Compatibility for SVE2 CodeCharlie Burnes2022/05/17 11:21 AM
                              Backward Compatibility for SVE2 CodeJörn Engel2022/05/17 02:11 PM
                                OpenMP SIMD DirectivesCharlie Burnes2022/05/17 04:05 PM
                                  OpenMP SIMD DirectivesJörn Engel2022/05/17 05:14 PM
                                    OpenMP SIMD DirectivesJan Wassenberg2022/05/20 10:12 PM
                                      OpenMP SIMD DirectivesFreddie2022/05/21 07:13 AM
                                        OpenMP SIMD DirectivesJan Wassenberg2022/05/21 10:54 PM
                                      OpenMP SIMD DirectivesJörn Engel2022/05/21 01:23 PM
                                        Alternative to Highway for code that is not SIMD width agnosticCharlie Burnes2022/05/21 10:11 PM
                                          Alternative to Highway for code that is not SIMD width agnosticJan Wassenberg2022/05/21 11:16 PM
                                            Alternative to Highway for code that is not SIMD width agnosticCharlie Burnes2022/05/22 06:30 AM
                                              Removal of NEONDoug S2022/05/22 10:57 AM
                                                Removal of NEONCharlie Burnes2022/05/22 01:12 PM
                                                Removal of NEON-.-2022/05/23 04:23 AM
                                                  Removal of NEONDoug S2022/05/23 08:08 AM
                                                    Removal of NEONdmcq2022/05/23 12:59 PM
                                                  Removal of NEONblaine2022/05/24 10:40 PM
                                              Alternative to Highway for code that is not SIMD width agnosticJan Wassenberg2022/05/22 12:06 PM
                                                Alternative to Highway for code that is not SIMD width agnosticCharlie Burnes2022/05/22 01:06 PM
                                                  Alternative to Highway for code that is not SIMD width agnosticJan Wassenberg2022/05/22 10:35 PM
                                              Alternative to Highway for code that is not SIMD width agnostic-.-2022/05/23 04:28 AM
                                          Alternative to Highway for code that is not SIMD width agnosticAdrian2022/05/22 05:04 AM
                                            Alternative to Highway for code that is not SIMD width agnosticCharlie Burnes2022/05/22 07:20 AM
                                          Alternative to Highway for code that is not SIMD width agnosticJörn Engel2022/05/22 01:13 PM
                                            Alternative to Highway for code that is not SIMD width agnosticCharlie Burnes2022/05/22 01:53 PM
                                              Alternative to Highway for code that is not SIMD width agnosticJörn Engel2022/05/22 02:49 PM
                                                Unaligned Loads and StoresCharlie Burnes2022/05/22 05:34 PM
                                                Alternative to Highway for code that is not SIMD width agnosticJan Wassenberg2022/05/22 10:46 PM
                                                  Unaligned Loads and StoresCharlie Burnes2022/05/23 12:46 AM
                                                    Unaligned Loads and StoresJan Wassenberg2022/05/23 05:34 AM
                                                  Is Highway a full compiler or yet another LLVM front-end, like icpc ? (NT)Michael S2022/05/23 01:12 AM
                                                    Is Highway a full compiler or yet another LLVM front-end, like icpc ?none2022/05/23 01:57 AM
                                                      Is Highway a full compiler or yet another LLVM front-end, like icpc ?Michael S2022/05/23 02:08 AM
                                                        Is Highway a full compiler or yet another LLVM front-end, like icpc ?Jan Wassenberg2022/05/23 05:38 AM
                                        OpenMP SIMD DirectivesJan Wassenberg2022/05/21 11:07 PM
                                          OpenMP SIMD DirectivesJörn Engel2022/05/22 01:25 PM
                                            OpenMP SIMD DirectivesJan Wassenberg2022/05/22 10:56 PM
                                              OpenMP SIMD DirectivesMichael S2022/05/23 02:32 AM
                                                OpenMP SIMD DirectivesJan Wassenberg2022/05/23 05:49 AM
                                                  OpenMP SIMD DirectivesMichael S2022/05/23 01:04 PM
                                                    OpenMP SIMD DirectivesJan Wassenberg2022/05/23 10:43 PM
                                        OpenMP SIMD Directivesanon22022/05/22 11:42 PM
                                          OpenMP SIMD DirectivesJörn Engel2022/05/23 12:11 AM
                                            OpenMP SIMD Directivesanon22022/05/23 12:47 AM
                                              TemplatesMichael S2022/05/23 02:52 AM
                                                Templatesanon22022/05/23 03:36 AM
                                                  At least use a handle unique in the thread you post in... (NT)anon22022/05/23 08:16 AM
                                              TemplatesJörn Engel2022/05/23 10:41 AM
                              Backward Compatibility for SVE2 Codeanonymou52022/05/17 02:36 PM
                                Lack of Backward Compatibility for Intel AVX512Charlie Burnes2022/05/17 03:22 PM
                                  Lack of Backward Compatibility for Intel AVX512anonymou52022/05/18 03:15 AM
                                    Lack of Backward Compatibility for Intel AVX512anon22022/05/18 03:36 AM
                                      Lack of Backward Compatibility for Intel AVX512anonymou52022/05/18 05:06 AM
                                        Lack of Backward Compatibility for Intel AVX512Michael S2022/05/18 05:36 AM
                                          Lack of Backward Compatibility for Intel AVX512me2022/05/18 05:50 AM
                                            Lack of Backward Compatibility for Intel AVX512Jukka Larja2022/05/18 06:47 AM
                                              Lack of Backward Compatibility for Intel AVX512me2022/05/18 09:18 AM
                                              Lack of Backward Compatibility for Intel AVX512Doug S2022/05/18 10:26 AM
                                                Lack of Backward Compatibility for Intel AVX512Brett2022/05/18 11:03 AM
                                                  Lack of Backward Compatibility for Intel AVX512me2022/05/18 11:35 AM
                                                    Lack of Backward Compatibility for Intel AVX512Jan Wassenberg2022/05/18 10:31 PM
                                                      Lack of Backward Compatibility for Intel AVX512Jukka Larja2022/05/19 05:58 AM
                                                        Lack of Backward Compatibility for Intel AVX512Jan Wassenberg2022/05/19 06:55 AM
                                                          Lack of Backward Compatibility for Intel AVX512Jukka Larja2022/05/19 11:09 AM
                                                            Why Is AVX 512 Useful for RPCS3?-.-2022/06/15 07:04 PM
                                                              Why Is AVX 512 Useful for RPCS3?Jukka Larja2022/06/15 09:33 PM
                                                    Lack of Backward Compatibility for Intel AVX512Jukka Larja2022/05/19 05:56 AM
                                                      Lack of Backward Compatibility for Intel AVX512Jan Wassenberg2022/05/19 06:49 AM
                                                        Lack of Backward Compatibility for Intel AVX512Jukka Larja2022/05/19 11:14 AM
                                                          Lack of Backward Compatibility for Intel AVX512Jan Wassenberg2022/05/19 12:19 PM
                                                            Lack of Backward Compatibility for Intel AVX512Jukka Larja2022/05/20 10:04 AM
                                                              Lack of Backward Compatibility for Intel AVX512zzyzx2022/05/20 01:48 PM
                                                                Lack of Backward Compatibility for Intel AVX512Jukka Larja2022/05/20 09:48 PM
                                                                  Lack of Backward Compatibility for Intel AVX512zzyzx2022/05/21 07:44 PM
                                                                    Lack of Backward Compatibility for Intel AVX512Jukka Larja2022/05/21 09:48 PM
                                                                      Lack of Backward Compatibility for Intel AVX512zzyzx2022/05/22 02:46 AM
                                                                        Lack of Backward Compatibility for Intel AVX512Jukka Larja2022/05/22 05:32 AM
                                                                          Lack of Backward Compatibility for Intel AVX512zzyzx2022/05/22 04:06 PM
                                                                            Lack of Backward Compatibility for Intel AVX512Jukka Larja2022/05/23 12:59 AM
                                                                              Lack of Backward Compatibility for Intel AVX512zzyzx2022/05/23 11:02 PM
                                                                                Lack of Backward Compatibility for Intel AVX512Jukka Larja2022/05/24 02:33 AM
                                                                                  Lack of Backward Compatibility for Intel AVX512zzyzx2022/05/24 03:18 PM
                                                                                    Lack of Backward Compatibility for Intel AVX512Jukka Larja2022/05/25 06:01 AM
                                                                                      Lack of Backward Compatibility for Intel AVX512zzyzx2022/05/25 03:02 PM
                                                      Lack of Backward Compatibility for Intel AVX512Eugene Nalimov2022/05/19 10:25 PM
                                                        Lack of Backward Compatibility for Intel AVX512Jukka Larja2022/05/20 09:34 AM
                                                  Lack of Backward Compatibility for Intel AVX512Jan Wassenberg2022/05/18 10:40 PM
                                                    Lack of Backward Compatibility for Intel AVX512Andrey2022/05/19 09:26 AM
                                                    Lack of Backward Compatibility for Intel AVX512Brett2022/05/19 11:23 AM
                                                      Lack of Backward Compatibility for Intel AVX512Andrey2022/05/19 01:50 PM
                                                        Lack of Backward Compatibility for Intel AVX512Brett2022/05/20 11:52 PM
                                                  Lack of Backward Compatibility for Intel AVX512Adrian2022/05/19 12:22 AM
                                                  Lack of Backward Compatibility for Intel AVX512Brendan2022/05/19 04:32 AM
                                                Lack of Backward Compatibility for Intel AVX512Jan Wassenberg2022/05/18 10:29 PM
                                                  Lack of Backward Compatibility for Intel AVX512Michael S2022/05/19 01:14 AM
                                                    Lack of Backward Compatibility for Intel AVX512Jan Wassenberg2022/05/19 07:02 AM
                                                      Lack of Backward Compatibility for Intel AVX512Michael S2022/05/19 08:13 AM
                                                        Lack of Backward Compatibility for Intel AVX512Jan Wassenberg2022/05/20 01:34 AM
                                                          Lack of Backward Compatibility for Intel AVX512Michael S2022/05/20 02:48 AM
                                                          OT Documentation on JPEG XL - site certificate brokenMichael S2022/05/20 03:17 AM
                                                            OT Documentation on JPEG XL - site certificate brokenJan Wassenberg2022/05/20 10:18 PM
                                                    Lack of Backward Compatibility for Intel AVX512-.-2022/05/20 03:55 AM
                                                      Lack of Backward Compatibility for Intel AVX512Michael S2022/05/20 05:51 AM
                                                        Lack of Backward Compatibility for Intel AVX512Jan Wassenberg2022/05/20 10:54 PM
                                                          Lack of Backward Compatibility for Intel AVX512Jan Wassenberg2022/05/20 10:57 PM
                                                            Lack of Backward Compatibility for Intel AVX512Michael S2022/05/21 10:57 AM
                                                              Lack of Backward Compatibility for Intel AVX512---2022/05/21 06:59 PM
                                                                Adding instructions to NEON??Doug S2022/05/22 11:01 AM
                                                                  Adding instructions to NEON??---2022/05/22 01:59 PM
                                                                    Adding instructions to NEON??Doug S2022/05/22 08:46 PM
                                                                      Adding instructions to NEON??Michael S2022/05/23 01:04 AM
                                                                        Adding instructions to NEON??anonymou52022/05/24 04:02 PM
                                                                      Adding instructions to NEON??Ungo2022/05/23 02:05 AM
                                                                        Adding instructions to NEON??---2022/05/23 06:49 AM
                                                                          Adding instructions to NEON??Ungo2022/05/23 09:01 PM
                                                                            Adding instructions to NEON??---2022/05/24 10:26 AM
                                                                      Adding instructions to NEON??---2022/05/23 06:56 AM
                                                                Lack of Backward Compatibility for Intel AVX512noko2022/05/23 12:29 PM
                                                              Lack of Backward Compatibility for Intel AVX512Jan Wassenberg2022/05/21 11:47 PM
                                                                Lack of Backward Compatibility for Intel AVX512Michael S2022/05/22 01:40 AM
                                                                  Lack of Backward Compatibility for Intel AVX512Jan Wassenberg2022/05/22 04:06 AM
                                                                    Lack of Backward Compatibility for Intel AVX512Michael S2022/05/22 05:12 AM
                                                                      Lack of Backward Compatibility for Intel AVX512Jan Wassenberg2022/05/22 05:53 AM
                                                                        Lack of Backward Compatibility for Intel AVX512Michael S2022/05/22 06:15 AM
                                                                          Lack of Backward Compatibility for Intel AVX512Jan Wassenberg2022/05/22 11:56 AM
                                              Lack of Backward Compatibility for Intel AVX512-.-2022/05/18 05:23 PM
                                                Sierra Forest Xeons - E Cores OnlyCharlie Burnes2022/05/19 03:11 AM
                                                  Sierra Forest Xeons - E Cores OnlyBrendan2022/05/19 04:42 AM
                                                    Sierra Forest Xeons - E Cores OnlyCharlie Burnes2022/05/19 05:30 AM
                                                      Sierra Forest Xeons - E Cores OnlyBrendan2022/05/20 04:06 AM
                                                        Sierra Forest Xeons - E Cores OnlyLinus Torvalds2022/05/20 11:32 AM
                                                          Sierra Forest Xeons - E Cores OnlyMark2022/05/20 12:15 PM
                                                            Sierra Forest Xeons - E Cores OnlyAndrey2022/05/20 03:34 PM
                                                            Sierra Forest Xeons - E Cores OnlyBrendan2022/05/20 05:29 PM
                                                            Sierra Forest Xeons - E Cores OnlyBjörn Ragnar Björnsson2022/05/20 05:54 PM
                                                              Sierra Forest Xeons - E Cores OnlyBrendan2022/05/20 08:42 PM
                                                                Sierra Forest Xeons - E Cores OnlyLinus Torvalds2022/05/21 12:06 AM
                                                                  Sierra Forest Xeons - E Cores Onlyanon22022/05/21 01:45 AM
                                                                    Sierra Forest Xeons - E Cores OnlyDoug S2022/05/21 12:33 PM
                                                                      Sierra Forest Xeons - E Cores OnlyBrett2022/05/21 05:18 PM
                                                                      Sierra Forest Xeons - E Cores Onlyanon22022/05/22 01:32 AM
                                                                  Sierra Forest Xeons - E Cores Onlyrwessel2022/05/21 05:05 AM
                                                                  Sierra Forest Xeons - E Cores OnlyBrendan2022/05/21 10:36 AM
                                                                    Sierra Forest Xeons - E Cores OnlyAndrey2022/05/21 11:30 AM
                                                                      Sierra Forest Xeons - E Cores OnlyBrendan2022/05/21 12:58 PM
                                                                        Sierra Forest Xeons - E Cores OnlyLinus Torvalds2022/05/21 04:58 PM
                                                                          Sierra Forest Xeons - E Cores Only-.-2022/05/21 07:03 PM
                                                                          Sierra Forest Xeons - E Cores OnlyBrendan2022/05/22 11:18 AM
                                                                            Sierra Forest Xeons - E Cores OnlyAndrey2022/05/22 04:18 PM
                                                                              Sierra Forest Xeons - E Cores OnlyBrendan2022/05/22 08:41 PM
                                                                                Sierra Forest Xeons - E Cores OnlyLinus Torvalds2022/05/22 09:49 PM
                                                                                  Proposal for heterogeneous runtime dispatchJan Wassenberg2022/05/22 11:11 PM
                                                                                    Proposal for heterogeneous runtime dispatchJörn Engel2022/05/22 11:51 PM
                                                                                      Proposal for heterogeneous runtime dispatchAdrian2022/05/23 12:25 AM
                                                                                        CorrectionAdrian2022/05/23 12:34 AM
                                                                                      Proposal for heterogeneous runtime dispatchJan Wassenberg2022/05/23 12:41 AM
                                                                                    Proposal for heterogeneous runtime dispatchUngo2022/05/23 01:27 AM
                                                                                      Proposal for heterogeneous runtime dispatchMichael S2022/05/23 03:14 AM
                                                                                      Heterogeneous ISA?Jan Wassenberg2022/05/23 06:11 AM
                                                                                        RISC-VPeter Lewis2022/05/30 03:45 PM
                                                                                          RISC-VHeikki Kultala2022/05/31 08:59 AM
                                                                                            RISC-VPeter Lewis2022/05/31 04:34 PM
                                                                                              RISC-VDoug S2022/06/01 12:45 AM
                                                                                                RISC-VPeter Lewis2022/06/01 03:55 PM
                                                                                                  RISC-VDoug S2022/06/01 09:50 PM
                                                                                                    RISC-V Eric Fink2022/06/02 12:20 AM
                                                                                                      Process...Anon2022/06/02 12:35 AM
                                                                                                        Process...Peter Lewis2022/06/02 01:54 AM
                                                                                                        Process...Michael S2022/06/02 04:42 AM
                                                                                                        Process...Eric Fink2022/06/02 05:43 AM
                                                                                                          Process...---2022/06/02 01:06 PM
                                                                                                            Process...Peter Lewis2022/06/02 02:01 PM
                                                                                                              Process... ItaniumRichard S2022/06/02 05:14 PM
                                                                                                                ItaniumPeter Lewis2022/06/02 06:07 PM
                                                                                                                  ItaniumRichard S2022/06/02 09:27 PM
                                                                                                                Process... ItaniumMichael S2022/06/03 04:39 AM
                                                                                                                  Process... ItaniumAdrian2022/06/03 05:26 AM
                                                                                                                    Process... ItaniumMichael S2022/06/03 06:32 AM
                                                                                                                      Process... ItaniumAdrian2022/06/03 07:14 AM
                                                                                                              Process...Doug S2022/06/02 10:54 PM
                                                                                                                Process...Peter Lewis2022/06/03 01:19 AM
                                                                                                            Process...Mark Roulo2022/06/02 08:15 PM
                                                                                                              Process...Michael S2022/06/03 05:06 AM
                                                                                                            Process...Brendan2022/06/02 09:13 PM
                                                                                                          Process...anon22022/06/02 04:13 PM
                                                                                                            Process...Eric Fink2022/06/02 10:00 PM
                                                                                                              Process...Michael S2022/06/03 05:16 AM
                                                                                                                Process...Doug S2022/06/03 08:57 AM
                                                                                                                  Process...James2022/06/04 04:46 AM
                                                                                                                    Process...Doug S2022/06/04 09:04 AM
                                                                                                                      Process...Anon42022/06/04 10:31 AM
                                                                                                                      Process...James2022/06/04 10:49 AM
                                                                                                          Process...Anon2022/06/05 02:55 AM
                                                                                                        There is no 5nm or 7nm anywhere.Heikki Kultala2022/06/02 10:45 AM
                                                                                                          There is no 5nm or 7nm anywhere.Doug S2022/06/02 11:10 AM
                                                                                                            There is no 5nm or 7nm anywhere.Heikki Kultala2022/06/02 11:50 AM
                                                                                                            There is no 5nm or 7nm anywhere.Peter Lewis2022/06/02 12:07 PM
                                                                                                            There is no 5nm or 7nm anywhere.anon22022/06/02 04:30 PM
                                                                                                          There is no 5nm or 7nm anywhere.Anon2022/06/05 01:41 AM
                                                                                                    RISC-VPeter Lewis2022/06/02 01:22 AM
                                                                                                      RISC-VFreddie2022/06/02 07:22 AM
                                                                                                        RISC-V---2022/06/02 01:25 PM
                                                                                                    RISC-VAdrian2022/06/02 01:47 AM
                                                                                                      RISC-VDoug S2022/06/02 11:18 AM
                                                                                                      x86 vs RISCHeikki Kultala2022/06/02 12:04 PM
                                                                                                        x86 vs RISCAnon2022/06/02 02:49 PM
                                                                                                          x86 vs RISCTim Mc2022/06/02 04:20 PM
                                                                                                          x86 vs RISCDoug S2022/06/02 11:01 PM
                                                                                                            x86 vs RISCAnon2022/06/05 01:55 AM
                                                                                                              x86 vs RISCPeter Lewis2022/06/05 04:23 PM
                                                                                                                x86 vs RISCAnon2022/06/05 04:32 PM
                                                                                                                Register Windows.Mark Roulo2022/06/06 09:56 AM
                                                                                                                  Register Windows.blaine2022/06/06 01:51 PM
                                                                                                                    S/W managed TLB missesMark Roulo2022/06/06 02:18 PM
                                                                                                                      S/W managed TLB missesMichael S2022/06/06 02:31 PM
                                                                                                                      S/W managed TLB missesblaine2022/06/06 11:53 PM
                                                                                                                      S/W managed TLB missesvonk2022/06/07 01:04 AM
                                                                                                                      S/W managed TLB missesDoug S2022/06/07 08:50 AM
                                                                                                                        S/W managed TLB missesanon22022/06/07 10:21 PM
                                                                                                                          S/W managed TLB missesJames2022/06/08 02:07 AM
                                                                                                                            S/W managed TLB missesMichael S2022/06/08 02:20 AM
                                                                                                                            S/W managed TLB missesanon22022/06/08 02:53 AM
                                                                                                                          Fairchild Clipper had h/w table walkPaul A. Clayton2022/06/09 12:46 PM
                                                                                                                            Fairchild Clipper had h/w table walkSimon Farnsworth2022/06/10 01:58 AM
                                                                                                                    Register Windows.anon22022/06/06 03:21 PM
                                                                                                        x86 vs RISCEric Fink2022/06/02 10:11 PM
                                                                                                          x86 vs RISCMichael S2022/06/03 06:49 AM
                                                                                                            x86 vs RISCBrett2022/06/03 12:32 PM
                                                                                                            x86 vs RISCAnon2022/06/05 02:23 AM
                                                                                                        x86 vs RISCAdrian2022/06/02 11:47 PM
                                                                                                      RISC-VAnon2022/06/02 02:33 PM
                                                                                                  RISC-V lifespan; encodings2022/06/04 11:39 AM
                                                                                                    µop CachePeter Lewis2022/06/04 06:56 PM
                                                                                                      x86 decode cores2022/06/05 12:32 AM
                                                                                                        x86 decode coresPeter Lewis2022/06/05 01:26 AM
                                                                                                        x86 decode coresPeter Lewis2022/06/06 04:22 AM
                                                                                                      µop CacheDoug S2022/06/05 11:08 AM
                                                                                                    RISC-V lifespan; encodingsEric Fink2022/06/05 04:26 AM
                                                                                                      RISC-V lifespan; encodings2022/06/05 07:37 AM
                                                                                                        RISC-V lifespan; encodingsanonymou52022/06/05 12:32 PM
                                                                                                          RISC-V lifespan; encodingsAnon2022/06/05 03:09 PM
                                                                                                          RISC-V lifespan; encodings2022/06/06 07:52 AM
                                                                                                            RISC-V lifespan; encodingsanonymou52022/06/06 08:07 AM
                                                                                                              RISC-V lifespan; encodingsAdrian2022/06/06 10:59 AM
                                                                                                                RISC-V lifespan; encodingsAnon2022/06/06 12:38 PM
                                                                                                                  RISC-V lifespan; encodingsAdrian2022/06/07 01:21 AM
                                                                                                                    RISC-V lifespan; encodingsMichael S2022/06/07 02:23 AM
                                                                                                                      RISC-V lifespan; encodingsAdrian2022/06/07 05:20 AM
                                                                                                                        RISC-V lifespan; encodingsBrett2022/06/07 06:04 PM
                                                                                                                          RISC-V lifespan; encodingsAnon2022/06/07 09:58 PM
                                                                                                                            RISC-V lifespan; encodings2022/06/08 08:07 AM
                                                                                                                              RISC-V lifespan; encodingsAnon2022/06/08 10:25 AM
                                                                                                                                RISC-V lifespan; encodings2022/06/08 12:07 PM
                                                                                                                RISC-V lifespan; encodingsBrett2022/06/06 01:50 PM
                                                                                                                  RISC-V lifespan; encodingsAdrian2022/06/07 12:59 AM
                                                                                                              RISC-V lifespan; encodingsAdrian2022/06/06 10:59 AM
                                                                                                              RISC-V lifespan; encodings2022/06/06 11:08 AM
                                                                                                    RISC-V lifespan; encodings---2022/06/05 06:12 PM
                                                                                                      RISC-V lifespan; encodingsAnon2022/06/05 06:48 PM
                                                                                                      RISC-V lifespan; encodingsJukka Larja2022/06/05 10:18 PM
                                                                                                        Profile-Guided OptimizationPeter Lewis2022/06/06 03:55 AM
                                                                                                          Profile-Guided Optimizationrwessel2022/06/06 05:26 AM
                                                                                                            Profile-Guided OptimizationDoug S2022/06/06 10:44 AM
                                                                                                              Profile-Guided OptimizationAndrew Clough2022/06/06 11:08 AM
                                                                                                              Profile-Guided Optimizationrwessel2022/06/06 11:57 AM
                                                                                                                Example of JIT cacheMark Roulo2022/06/06 02:10 PM
                                                                                                                  Example of JIT cacherwessel2022/06/06 02:59 PM
                                                                                                                    Example of JIT cacheMark Roulo2022/06/07 06:40 AM
                                                                                                                      Example of JIT cacherwessel2022/06/07 07:46 AM
                                                                                                              Profile-Guided OptimizationSimon Farnsworth2022/06/07 02:47 AM
                                                                                                          Profile-Guided OptimizationJukka Larja2022/06/06 08:42 PM
                                                                                                      Accurate branch prediction is not everythingPaul A. Clayton2022/06/14 11:48 AM
                                                                                                        Accurate branch prediction is not everything---2022/06/14 01:40 PM
                                                                                                          Accurate branch prediction is not everythingJames2022/06/14 03:41 PM
                                                                                                        Accurate branch prediction is not everythingdmcq2022/06/15 09:38 AM
                                                                                                          Accurate branch prediction is not everythingnone2022/06/15 09:57 AM
                                                                                                            Accurate branch prediction is not everythingdmcq2022/06/15 10:23 AM
                                                                                                            Accurate branch prediction is not everythingDoug S2022/06/15 01:55 PM
                                                                                                              Accurate branch prediction is not everythingdmcq2022/06/15 04:38 PM
                                                                                                Adding Neural Engines to x86Peter Lewis2022/06/04 07:06 PM
                                                                                                  Adding Neural Engines to x86Freddie2022/06/05 12:07 PM
                                                                                                    Adding Neural Engines to x86Peter Lewis2022/06/05 04:20 PM
                                                                                                      Adding Neural Engines to x86---2022/06/05 06:40 PM
                                                                                                        Adding Neural Engines to x86Peter Lewis2022/06/05 09:22 PM
                                                                                                  Adding Neural Engines to x86---2022/06/05 06:34 PM
                                                                                                    Missing metricsAnon2022/06/05 06:59 PM
                                                                                                    Adding Neural Engines to x86Peter Lewis2022/06/06 03:41 AM
                                                                                            RISC-VJan Wassenberg2022/05/31 10:00 PM
                                                                                              RISC-VPeter Lewis2022/06/01 04:02 PM
                                                                                                RISC-VJan Wassenberg2022/06/01 10:17 PM
                                                                                              RISC-V Eric Fink2022/06/02 12:25 AM
                                                                                                RISC-VJan Wassenberg2022/06/02 11:10 PM
                                                                                                  RISC-VEric Fink2022/06/03 12:23 AM
                                                                                                    RISC-VJan Wassenberg2022/06/03 11:10 PM
                                                                                                      RISC-VJukka Larja2022/06/04 12:15 AM
                                                                                                        RISC-VJan Wassenberg2022/06/04 11:23 PM
                                                                                                      RISC-VEric Fink2022/06/04 05:59 AM
                                                                                                        RISC-VJan Wassenberg2022/06/04 11:14 PM
                                                                                                    RISC-VLinus Torvalds2022/06/04 10:17 AM
                                                                                                      RISC-V-.-2022/06/04 05:56 PM
                                                                                                        RISC-VLinus Torvalds2022/06/04 08:00 PM
This Post has been deleted
                                                                                                      RISC-VEric Fink2022/06/05 04:31 AM
                                                                                                        SIMD in parsingWilco2022/06/05 05:40 AM
                                                                                                          SIMD in parsingFoo_2022/06/06 02:19 AM
                                                                                                            SIMD in parsingMichael S2022/06/06 02:43 AM
                                                                                                              SIMD in parsingLinus Torvalds2022/06/06 09:40 AM
                                                                                                          SIMD in parsing-.-2022/06/08 05:28 AM
                                                                                              RISC-V V-extensionHeikki Kultala2022/06/02 10:40 AM
                                                                                                RISC-V V-extensionJan Wassenberg2022/06/02 11:09 PM
                                                                                            RISC-VPer Hesselgren2022/06/01 05:40 AM
                                                                                    Proposal for heterogeneous runtime dispatchBrendan2022/05/23 01:51 AM
                                                                                    Proposal for heterogeneous runtime dispatchBrendan2022/05/23 01:51 AM
                                                                                      Proposal for heterogeneous runtime dispatchBjörn Ragnar Björnsson2022/05/23 05:41 PM
                                                                                        Proposal for heterogeneous runtime dispatchJan Wassenberg2022/05/23 10:38 PM
                                                                                          Proposal for heterogeneous runtime dispatchJukka Larja2022/05/24 02:48 AM
                                                                                            Proposal for heterogeneous runtime dispatchJan Wassenberg2022/05/24 04:35 AM
                                                                                              Proposal for heterogeneous runtime dispatchJukka Larja2022/05/24 07:38 AM
                                                                                                Proposal for heterogeneous runtime dispatchJan Wassenberg2022/05/29 12:51 AM
                                                                                          Proposal for heterogeneous runtime dispatchMichael S2022/05/24 03:48 AM
                                                                                            SIMD applicabilityJan Wassenberg2022/05/24 04:50 AM
                                                                                              Don't mix up SIMD support with AVX2 vs AVX-512 heterogeneityMark Roulo2022/05/24 07:41 AM
                                                                                                Don't mix up SIMD support with AVX2 vs AVX-512 heterogeneityJan Wassenberg2022/05/24 11:23 AM
                                                                                                  Don't mix up SIMD support with AVX2 vs AVX-512 heterogeneitySimon Farnsworth2022/05/24 01:56 PM
                                                                                                Don't mix up SIMD support with AVX2 vs AVX-512 heterogeneityBrendan2022/05/24 05:09 PM
                                                                                                  Don't mix up SIMD support with AVX2 vs AVX-512 heterogeneityDoug S2022/05/24 10:03 PM
                                                                                                    Don't mix up SIMD support with AVX2 vs AVX-512 heterogeneityBrendan2022/05/25 05:37 PM
                                                                                                  Don't mix up SIMD support with AVX2 vs AVX-512 heterogeneityJukka Larja2022/05/25 06:24 AM
                                                                                                    Don't mix up SIMD support with AVX2 vs AVX-512 heterogeneityBrendan2022/05/25 06:16 PM
                                                                                                      Don't mix up SIMD support with AVX2 vs AVX-512 heterogeneityJukka Larja2022/05/25 08:50 PM
                                                                                            Proposal for heterogeneous runtime dispatchAdrian2022/05/24 02:39 PM
                                                                                              Proposal for heterogeneous runtime dispatchJörn Engel2022/05/24 09:41 PM
                                                                                              Proposal for heterogeneous runtime dispatchJan Wassenberg2022/05/29 12:51 AM
                                                                                                Proposal for heterogeneous runtime dispatchAdrian2022/05/29 04:33 AM
                                                                                                  Proposal for heterogeneous runtime dispatchAdrian2022/05/29 04:48 AM
                                                                                                  Proposal for heterogeneous runtime dispatchJan Wassenberg2022/05/29 11:05 AM
                                                                                                    Proposal for heterogeneous runtime dispatchAdrian2022/05/29 01:39 PM
                                                                                                      turbostat instructionsJan Wassenberg2022/05/29 10:51 PM
                                                                                                  Proposal for heterogeneous runtime dispatchSome dude2022/05/30 12:04 PM
                                                                                          Proposal for heterogeneous runtime dispatchSimon Farnsworth2022/05/24 04:21 AM
                                                                                  Sierra Forest Xeons - E Cores OnlyBrendan2022/05/23 12:41 AM
                                                                                    Sierra Forest Xeons - E Cores OnlySimon Farnsworth2022/05/23 03:03 AM
                                                                                      Sierra Forest Xeons - E Cores OnlyBrendan2022/05/23 09:12 AM
                                                                                        Sierra Forest Xeons - E Cores OnlySimon Farnsworth2022/05/24 04:18 AM
                                                                                          Sierra Forest Xeons - E Cores Onlyrwessel2022/05/24 08:22 AM
                                                                                    Sierra Forest Xeons - E Cores OnlyLinus Torvalds2022/05/23 12:30 PM
                                                                                      Sierra Forest Xeons - E Cores OnlyBrendan2022/05/23 01:13 PM
                                                                                        Sierra Forest Xeons - E Cores OnlyLinus Torvalds2022/05/23 04:54 PM
                                                                                          Sierra Forest Xeons - E Cores Only2022/05/24 11:49 AM
                                                                                            Sierra Forest Xeons - E Cores OnlyLinus Torvalds2022/05/24 12:11 PM
                                                                                              Sierra Forest Xeons - E Cores Only2022/05/24 03:12 PM
                                                                                                Sierra Forest Xeons - E Cores OnlyLinus Torvalds2022/05/24 04:33 PM
                                                                                          Sierra Forest Xeons - E Cores OnlyBrendan2022/05/24 01:44 PM
                                                                                            Sierra Forest Xeons - E Cores OnlySimon Farnsworth2022/05/24 02:14 PM
                                                                                              Sierra Forest Xeons - E Cores Only2022/05/24 03:37 PM
                                                                                                Sierra Forest Xeons - E Cores OnlyJames2022/05/26 03:42 AM
                                                                                              Sierra Forest Xeons - E Cores OnlyBrendan2022/05/24 09:53 PM
                                                                                              Sierra Forest Xeons - E Cores OnlyJörn Engel2022/05/25 12:09 AM
                                                                                                Sierra Forest Xeons - E Cores OnlySimon Farnsworth2022/05/25 02:27 AM
                                                                                                  Sierra Forest Xeons - E Cores OnlyJan Wassenberg2022/05/29 12:49 AM
                                                                                                    Sierra Forest Xeons - E Cores OnlyMichael S2022/05/29 02:15 AM
                                                                                                      Sierra Forest Xeons - E Cores OnlyLinus Torvalds2022/05/29 10:48 AM
                                                                                                        Sierra Forest Xeons - E Cores Onlyanonymou52022/05/29 11:35 AM
                                                                                                          Sierra Forest Xeons - E Cores OnlyLinus Torvalds2022/05/30 11:07 AM
                                                                                                            Sierra Forest Xeons - E Cores Onlyanonymou52022/05/30 12:46 PM
                                                                                                        Sierra Forest Xeons - E Cores OnlyMichael S2022/05/29 11:59 AM
                                                                                                      Sierra Forest Xeons - E Cores OnlyJan Wassenberg2022/05/29 11:20 AM
                                                                                                        Sierra Forest Xeons - E Cores OnlyMichael S2022/05/29 01:38 PM
                                                                                                          Sierra Forest Xeons - E Cores OnlyJörn Engel2022/05/29 02:10 PM
                                                                                                          Sierra Forest Xeons - E Cores Only-.-2022/05/29 05:28 PM
                                                                                                            Sierra Forest Xeons - E Cores OnlyMichael S2022/05/30 01:32 AM
                                                                                                              Sierra Forest Xeons - E Cores Only-.-2022/05/30 02:44 AM
                                                                                                                Sierra Forest Xeons - E Cores OnlyMichael S2022/05/30 03:12 AM
                                                                                                                  Sierra Forest Xeons - E Cores Only-.-2022/05/30 05:46 AM
                                                                                                          Sierra Forest Xeons - E Cores OnlyJan Wassenberg2022/05/29 10:48 PM
                                                                                                            quick radix mergeMichael S2022/05/30 01:02 AM
                                                                                                              quick radix mergeJan Wassenberg2022/05/30 07:16 AM
                                                                                                                quick radix mergeMichael S2022/05/30 08:36 AM
                                                                                                                  quick radix mergeJan Wassenberg2022/05/30 10:07 PM
                                                                                                                quick radix mergerwessel2022/05/30 09:36 AM
                                                                                      Sierra Forest Xeons - E Cores OnlyChristian Bornträger2022/05/24 08:06 AM
                                                                                        Sierra Forest Xeons - E Cores Onlyrwessel2022/05/24 08:40 AM
                                                                          Sierra Forest Xeons - E Cores Only2022/05/22 11:51 AM
                                                                            Sierra Forest Xeons - E Cores OnlyDoug S2022/05/22 08:52 PM
                                                                              Linux doesn't have a plan for hetero-ISA CPUs2022/05/23 06:03 AM
                                                                                Linux doesn't have a plan for hetero-ISA CPUsDoug S2022/05/23 08:35 AM
                                                                                  Linux doesn't have a plan for hetero-ISA CPUsBrendan2022/05/23 11:44 AM
                                                                                    Linux doesn't have a plan for hetero-ISA CPUsGionatan Danti2022/05/24 06:29 AM
                                                                            Sierra Forest Xeons - E Cores OnlySimon Farnsworth2022/05/23 04:16 AM
                                                                    Sierra Forest Xeons - E Cores OnlyJukka Larja2022/05/21 10:23 PM
                                                          well said (NT)Michael S2022/05/21 11:48 AM
                                                  Sierra Forest Xeons - E Cores OnlyMichael S2022/05/19 05:00 AM
                                                  Sierra Forest Xeons - E Cores Only-.-2022/05/19 06:25 AM
                                                    Sierra Forest Xeons - E Cores OnlyMichael S2022/05/20 06:29 AM
                                                  Sierra Forest Xeons - E Cores Onlyanonymou52022/05/19 09:46 AM
                                                    Sierra Forest Xeons - E Cores OnlyCharlie Burnes2022/05/19 02:19 PM
                                                      Sierra Forest Xeons - E Cores OnlyAdrian2022/05/20 12:29 AM
                                              Lack of Backward Compatibility for Intel AVX512Adrian2022/05/18 11:57 PM
                                                Lack of Backward Compatibility for Intel AVX512Brett2022/05/19 10:55 AM
                                                  Lack of Backward Compatibility for Intel AVX512Michael S2022/05/19 11:53 AM
                                                  Lack of Backward Compatibility for Intel AVX512Adrian2022/05/20 12:38 AM
                              Backward Compatibility for SVE2 Code---2022/05/17 02:57 PM
                                Backward Compatibility for SVE2 CodeCharlie Burnes2022/05/17 04:12 PM
                                Backward Compatibility for SVE2 Codeanon12022/05/18 02:44 AM
                                  Backward Compatibility for SVE2 CodeSimon Farnsworth2022/05/18 03:03 AM
                                    Backward Compatibility for SVE2 CodeDoug S2022/05/18 10:14 AM
                                      Backward Compatibility for SVE2 Codedmcq2022/05/20 05:43 AM
                                        Backward Compatibility for SVE2 CodeDoug S2022/05/20 10:07 AM
                                          Backward Compatibility for SVE2 Codedmcq2022/05/21 08:35 AM
                                            Backward Compatibility for SVE2 Codedmcq2022/05/21 08:57 AM
                                  Backward Compatibility for SVE2 Code---2022/05/18 09:56 AM
                      Backward Compatibility for SVE2 CodeJan Wassenberg2022/05/17 12:26 PM
                        Backward Compatibility for SVE2 Code---2022/05/17 03:01 PM
                        Use of Highway to provide backward compatibilityCharlie Burnes2022/05/18 03:55 PM
                          Use of Highway to provide backward compatibilityBrett2022/05/18 08:57 PM
                            Use of Highway to provide backward compatibilityJan Wassenberg2022/05/18 10:16 PM
                              Use of Highway to provide backward compatibilityCharlie Burnes2022/05/18 11:03 PM
                                Use of Highway to provide backward compatibilityBrett2022/05/18 11:20 PM
                                  Use of Highway to provide backward compatibility---2022/05/19 01:20 PM
                                    Use of Highway to provide backward compatibilityCharlie Burnes2022/05/19 03:05 PM
                                      Use of Highway to provide backward compatibilityBrett2022/05/19 04:18 PM
                                        Use of Highway to provide backward compatibilityCharlie Burnes2022/05/19 07:29 PM
                                          Use of Highway to provide backward compatibilityJan Wassenberg2022/05/19 09:12 PM
                                            Use of Highway to provide backward compatibilityBrett2022/05/19 10:38 PM
                                            Use of Highway to provide backward compatibilityCharlie Burnes2022/05/21 07:48 AM
                                              Use of Highway to provide backward compatibilityCharlie Burnes2022/05/21 12:36 PM
                                              Use of Highway to provide backward compatibilityJan Wassenberg2022/05/21 10:45 PM
                                                Use of Highway to provide backward compatibilityCharlie Burnes2022/05/22 07:52 AM
        Questions About Apple's AVX512dmcq2022/05/13 04:24 PM
      Questions About Apple's AVX512Matt Lohmann2022/05/13 01:32 PM
        Questions About Apple's AVX512---2022/05/13 02:09 PM
        Questions About Apple's AVX512Anon12022/05/13 03:55 PM
          Questions About Apple's AVX512Matt Lomann2022/05/13 07:02 PM
            Questions About Apple's AVX512---2022/05/13 09:03 PM
            Questions About Apple's AVX512Simon Farnsworth2022/05/14 06:11 AM
              Questions About Apple's AVX512---2022/05/14 12:06 PM
        Questions About Apple's AVX512Adrian2022/05/14 12:35 AM
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