Saltwell Outperforming A15...With Less Power!!!

By: Wilco (Wilco.Dijkstra.delete@this.ntlworld.com), July 11, 2013 7:26 am
Room: Moderated Discussions
none (none.delete@this.none.com) on July 11, 2013 5:12 am wrote:
> Wilco (Wilco.Dijkstra.delete@this.ntlworld.com) on July 11, 2013 5:03 am wrote:
> [...]
> > Which benchmark is affected by denormals? I thought pretty much any modern
> > CPU nowadays deals with denormals in hardware with minimal penalty...
>
> That's an Intel claim, so I can't say. I have no reason not to believe it.

Alright. I would personally want to see some hard evidence, such as which benchmarks are affected and by how much. The 2 FP benchmarks where Atom does really bad are blur and sharpen image, but it's hard to see how you could accidentally make a simple filter use denormals.

> [...]
> > Yes, GCC can still generate some inefficient code at times, especially the array accesses look
> > bad... The Intel version is vectorized, which means the ARM version will be about twice as
> > fast again when built with Neon. So yes, setting compiler options etc right matters...
>
> The x86 loop I showed is scalar. There's a vectored one in Geekbench, for x86 only, but I'm not
> sure it's ever run (and if it is, then Saltwell stinks even more than what Geekbench shows).

OK. I forgot to mention - although the code looks very inefficient, the extra instructions don't matter that much on a wide OoO core. There are 9 instructions in the ARM inner loop, so they take 3 cycles to decode, issue and execute on A15. What determines the actual cycles per iteration is the latency of vmla. With unrolling (also not enabled - was this compiled -Os?!?) and vectorization it could probably run 8 times faster - it's why these loops are typically hand optimized...

Wilco
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ARM at Computexanon2013/06/03 08:54 AM
  ARM at ComputexExophase2013/06/03 09:31 AM
    ARM at ComputexWilco2013/06/03 10:52 AM
      ARM at ComputexExophase2013/06/03 12:02 PM
        ARM at Computexnone2013/06/03 01:28 PM
          ARM at ComputexAlberto2013/06/04 10:41 AM
            ARM at Computexanon2013/06/04 01:36 PM
              ARM at ComputexWilco2013/06/04 03:56 PM
                ARM at ComputexDavid Kanter2013/06/04 04:51 PM
                  ARM at ComputexNobodyatAll2013/06/04 05:53 PM
                  ARM at Computexanon2013/06/04 06:53 PM
        ARM at ComputexWilco2013/06/03 01:47 PM
    ARM at Computexanon2013/06/04 04:03 AM
      ARM at ComputexDavid Kanter2013/06/04 08:16 AM
      ARM at ComputexExophase2013/06/04 10:36 AM
        ARM at ComputexWilco2013/06/04 04:09 PM
          ARM at ComputexNobodyatAll2013/06/04 04:23 PM
          ARM at ComputexDavid Kanter2013/06/04 05:00 PM
            ARM at Computexnone2013/06/05 05:26 AM
              ARM at Computexanon2013/06/05 07:19 AM
              ARM at Computexaaron spink2013/06/05 03:04 PM
                Saltwell Outperforming A15...With Less Power!!!Jason2013/06/07 01:56 PM
                  Saltwell Outperforming A15...With Less Power!!!John2013/06/08 06:28 AM
                    Saltwell Outperforming A15...With Less Power!!!Kevin G2013/06/08 02:18 PM
                      Saltwell Outperforming A15...With Less Power!!!David Kanter2013/06/08 08:43 PM
                      Saltwell Outperforming A15...With Less Power!!!tarlinian2013/06/09 02:00 PM
                        Saltwell Outperforming A15...With Less Power!!!none2013/06/09 03:11 PM
                          Saltwell Outperforming A15...With Less Power!!!none2013/07/10 11:46 AM
                            Saltwell Outperforming A15...With Less Power!!!Wilco2013/07/10 07:59 PM
                              Saltwell Outperforming A15...With Less Power!!!Klimax2013/07/10 10:03 PM
                                Saltwell Outperforming A15...With Less Power!!!anon2013/07/10 10:29 PM
                                  Saltwell Outperforming A15...With Less Power!!!Klimax2013/07/10 11:30 PM
                                    Saltwell Outperforming A15...With Less Power!!!Wilco2013/07/11 01:04 AM
                                      Saltwell Outperforming A15...With Less Power!!!Klimax2013/07/11 03:10 AM
                                        Saltwell Outperforming A15...With Less Power!!!anon2013/07/11 04:10 AM
                                        Saltwell Outperforming A15...With Less Power!!!Wilco2013/07/11 04:43 AM
                                        Saltwell Outperforming A15...With Less Power!!!Steve2013/07/14 08:10 PM
                                          Saltwell Outperforming A15...With Less Power!!!Klimax2013/07/14 10:55 PM
                                          Saltwell Outperforming A15...With Less Power!!!bakaneko2013/07/15 02:03 AM
                                            Saltwell Outperforming A15...With Less Power!!!anon2013/07/16 01:07 AM
                                              Saltwell Outperforming A15...With Less Power!!!bakaneko2013/07/16 06:25 AM
                                                Saltwell Outperforming A15...With Less Power!!!none2013/07/16 06:34 AM
                                                Saltwell Outperforming A15...With Less Power!!!Exophase2013/07/16 10:34 AM
                                                  Saltwell Outperforming A15...With Less Power!!!bakaneko2013/07/18 02:24 PM
                                                    Saltwell Outperforming A15...With Less Power!!!none2013/07/18 03:26 PM
                                    Saltwell Outperforming A15...With Less Power!!!anon2013/07/11 02:50 AM
                                      Saltwell Outperforming A15...With Less Power!!!Klimax2013/07/11 11:25 PM
                                        Saltwell Outperforming A15...With Less Power!!!anon2013/07/11 11:45 PM
                                          Saltwell Outperforming A15...With Less Power!!!Klimax2013/07/12 12:10 AM
                                            Saltwell Outperforming A15...With Less Power!!!anon2013/07/12 01:52 AM
                                    Saltwell Outperforming A15...With Less Power!!!Gabriele Svelto2013/07/11 04:20 AM
                                      Saltwell Outperforming A15...With Less Power!!!Klimax2013/07/11 11:51 PM
                                Saltwell Outperforming A15...With Less Power!!!bakaneko2013/07/11 12:02 AM
                                  Saltwell Outperforming A15...With Less Power!!!Klimax2013/07/11 12:28 AM
                                    Saltwell Outperforming A15...With Less Power!!!none2013/07/11 01:49 AM
                                      Saltwell Outperforming A15...With Less Power!!!Klimax2013/07/11 03:00 AM
                                        Saltwell Outperforming A15...With Less Power!!!Klimax2013/07/11 03:02 AM
                                        Saltwell Outperforming A15...With Less Power!!!none2013/07/11 04:44 AM
                                          Saltwell Outperforming A15...With Less Power!!!Michael S2013/07/11 05:33 AM
                                            Saltwell Outperforming A15...With Less Power!!!none2013/07/11 05:58 AM
                                              Saltwell Outperforming A15...With Less Power!!!none2013/07/11 05:59 AM
                                              Saltwell Outperforming A15...With Less Power!!!Wilco2013/07/11 07:40 AM
                                                Saltwell Outperforming A15...With Less Power!!!Michael S2013/07/11 08:34 AM
                                                  Saltwell Outperforming A15...With Less Power!!!none2013/07/11 08:50 AM
                                              Saltwell Outperforming A15...With Less Power!!!Michael S2013/07/11 09:02 AM
                                          Saltwell Outperforming A15...With Less Power!!!Klimax2013/07/11 10:11 PM
                                      Saltwell Outperforming A15...With Less Power!!!Michael S2013/07/11 04:12 AM
                                        Saltwell Outperforming A15...With Less Power!!!none2013/07/11 04:51 AM
                                          Saltwell Outperforming A15...With Less Power!!!Wilco2013/07/11 05:03 AM
                                            Saltwell Outperforming A15...With Less Power!!!none2013/07/11 05:12 AM
                                              Saltwell Outperforming A15...With Less Power!!!Wilco2013/07/11 07:26 AM
                                                Saltwell Outperforming A15...With Less Power!!!none2013/07/11 08:29 AM
                                                Saltwell Outperforming A15...With Less Power!!!Wilco2013/07/12 04:08 AM
                                                  Saltwell Outperforming A15...With Less Power!!!Michael S2013/07/12 04:25 AM
                                              Saltwell Outperforming A15...With Less Power!!!Klimax2013/07/11 11:55 PM
                                                Saltwell Outperforming A15...With Less Power!!!Megol2013/07/13 07:20 AM
                                    Java/Dalvik benchmarksbakaneko2013/07/11 02:26 AM
                                  Saltwell Outperforming A15...With Less Power!!!Linus Torvalds2013/07/11 10:57 AM
                                    Saltwell Outperforming A15...With Less Power!!!Linus Torvalds2013/07/11 11:20 AM
                                      Saltwell Outperforming A15...With Less Power!!!Ian Ameline2013/07/11 03:20 PM
                                      Saltwell Outperforming A15...With Less Power!!!Sylvain Collange2013/07/12 02:29 AM
                                        Saltwell Outperforming A15...With Less Power!!!Wilco2013/07/12 03:51 AM
                                          Saltwell Outperforming A15...With Less Power!!!Sylvain Collange2013/07/12 06:00 AM
                                      Saltwell Outperforming A15...With Less Power!!!bakaneko2013/07/12 03:28 AM
                                        Saltwell Outperforming A15...With Less Power!!!Linus Torvalds2013/07/12 09:11 AM
                                          Saltwell Outperforming A15...With Less Power!!!bakaneko2013/07/12 10:12 AM
                                          Saltwell Outperforming A15...With Less Power!!!2013/07/12 10:48 AM
                                            Saltwell Outperforming A15...With Less Power!!!Linus Torvalds2013/07/12 11:14 AM
                                              JIT2013/07/13 05:50 AM
                                                How'd you get this flower symbol as your user name ?anon2013/07/13 09:20 AM
                                                  How'd you get this flower symbol as your user name ?Doug S Ꭳ❂〄☢⚓♜☎♬⚄☠2013/07/13 10:12 AM
                                                JITx2013/07/15 06:43 AM
                                    Not reallyAnon2013/07/11 11:21 AM
                                    consistency, pleaseMichael S2013/07/11 11:22 AM
                                      consistency, pleaseLinus Torvalds2013/07/11 11:52 AM
                                        consistency, pleaseMichael S2013/07/11 02:43 PM
                                          consistency, pleaseLinus Torvalds2013/07/11 03:12 PM
                                            consistency, pleaseMark Roulo2013/07/11 03:54 PM
                                              the discussion was about absence of AVX in Silvermont (NT)Michael S2013/07/11 03:59 PM
                                                the discussion was about absence of AVX in SilvermontMark Roulo2013/07/11 04:19 PM
                                                  the discussion was about absence of AVX in SilvermontLinus Torvalds2013/07/12 09:16 AM
                                                    Thank youMark Roulo2013/07/12 09:58 AM
                                                    the discussion was about absence of AVX in Silvermontanon2013/07/12 10:10 AM
                                                      Not really (again)Anon2013/07/12 10:26 AM
                                                        Not really (again)anon2013/07/12 05:40 PM
                                                    the discussion was about absence of AVX in SilvermontLinus Torvalds2013/07/12 10:31 AM
                                                      you are wrong at about 100% of you saidMichael S2013/07/13 11:22 AM
                                                        you are wrong at about 100% of you saidLinus Torvalds2013/07/13 12:08 PM
                                                          you are wrong at about 100% of you saidMichael S2013/07/13 01:13 PM
                                                            you are wrong at about 100% of you saidLinus Torvalds2013/07/13 02:11 PM
                                                            you are wrong at about 100% of you saidvvid2013/07/13 03:20 PM
                                                              you are wrong at about 100% of you saidMichael S2013/07/14 01:38 AM
                                    Saltwell Outperforming A15...With Less Power!!!anon2013/07/11 06:41 PM
                                    Saltwell Outperforming A15...With Less Power!!!bakaneko2013/07/12 03:22 AM
                  Round 2: Baytrail benchmark (yes Antutu!) crushes Snapdragon 800.sammy2013/07/12 11:28 AM
                    Round 2: AnTuTu scores drop dramatically for AtomWilco2013/07/12 11:59 AM
                      Round 2: AnTuTu scores drop dramatically for AtomSteve2013/07/14 08:16 PM
                        Round 2: AnTuTu scores drop dramatically for AtomKlimax2013/07/14 10:59 PM
                        Round 2: AnTuTu scores drop dramatically for AtomDavid Kanter2013/07/15 01:57 PM
                          Intel is cheating AnTuTuWilco2013/07/15 03:43 PM
                            Intel is cheating AnTuTubakaneko2013/07/15 07:47 PM
                              Intel is cheating AnTuTuLinus Torvalds2013/07/15 08:45 PM
                                Intel is cheating AnTuTubakaneko2013/07/16 02:42 AM
                                  Intel is cheating AnTuTuWilco2013/07/16 03:47 AM
                                    Intel is cheating AnTuTubakaneko2013/07/16 05:50 AM
                                      Intel is cheating AnTuTuWilco2013/07/17 03:33 PM
                                        Intel is cheating AnTuTuKlimax2013/07/17 11:29 PM
                                          Intel is cheating AnTuTunone2013/07/17 11:35 PM
                                            Intel is cheating AnTuTuKlimax2013/07/18 01:41 AM
                                              Intel is cheating AnTuTuanon2013/07/18 02:10 AM
                                                Intel is cheating AnTuTuMichael S2013/07/18 03:39 AM
                                                Intel is cheating AnTuTuWilco2013/07/18 04:07 AM
                                                  Intel is cheating AnTuTunone2013/07/18 04:15 AM
                                                    Intel is cheating AnTuTuWilco2013/07/18 05:18 AM
                                                    Intel is cheating AnTuTuMichael S2013/07/18 06:44 AM
                                                      Intel is cheating AnTuTunone2013/07/18 07:47 AM
                                                        strict aliasingMichael S2013/07/18 08:10 AM
                                                          strict aliasing rules have existed since C89 (NT)Ricardo B2013/07/18 05:28 PM
                                                  Intel is cheating AnTuTuKlimax2013/07/18 11:30 AM
                                                Intel is cheating AnTuTuKlimax2013/07/18 11:39 AM
                                                  Intel is cheating AnTuTuanon2013/07/18 12:05 PM
                                                    Intel is cheating AnTuTuKlimax2013/07/20 12:05 AM
                                                      Intel is cheating AnTuTunone2013/07/20 02:50 AM
                                                  Intel is cheating AnTuTunone2013/07/18 12:38 PM
                                                    Intel is cheating AnTuTuKlimax2013/07/19 11:57 PM
                                  Intel is cheating AnTuTuLinus Torvalds2013/07/16 12:32 PM
                                Intel is cheating AnTuTu2013/07/16 03:16 AM
                                  Intel is cheating AnTuTubakaneko2013/07/16 04:55 AM
                                    Intel is cheating AnTuTuWilco2013/07/17 03:46 PM
                                      Intel is cheating AnTuTubakaneko2013/07/18 02:05 PM
                                      Intel is cheating AnTuTuDavid Kanter2013/07/19 02:31 AM
                          Round 2: AnTuTu scores drop dramatically for Atomanon2013/07/15 04:43 PM
                            Round 2: AnTuTu scores drop dramatically for Atomnone2013/07/16 12:15 AM
                          Round 2: AnTuTu scores drop dramatically for AtomGroo2013/07/16 07:35 AM
        ARM at Computexanon2013/06/04 10:43 PM
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