So, what do people think of these numbers>

By: Linus Torvalds (torvalds.delete@this.linux-foundation.org), April 20, 2012 10:05 am
Room: Moderated Discussions
Kira (kirsc@aeterna.ru) on 4/20/12 wrote:
>
>What about Power4 through Power6, which were also fairly
>picky about optimization? Were they "broken" uarches?

I think POWER6 was indeed fairly broken, but it damn well
made up for it with high frequencies and ultimately good
performance. So it did the whole P4 thing, but without
quite as much fragility.

But yes, I definitely think POWER7 is the better uarch.

POWER5 I thought was quite reasonable, although iirc it
still had that odd 2-cycle integer latency from POWER4.

In the end, some amount of fragility in performance
is quite acceptable. There are always going to be things
that perform better on one uarch over another. And it is
possible that the benchmarks that phoronix picked are ones
that show up certain unimportant special cases more than
they really should matter.

And if the performance fragility is of the type where you
generally perform quite well, but then have a few cases
where you are truly outstanding, nobody is going to'
complain.

So in the end, performance matters most. If you are the
unquestioned top performer, and the fragility just sometimes
means that it's not as obvious than at other times, I'd
be crazy to complain.

But if it's a matter of "pretty ho-hum performance, but
then sometimes if things line up just right you look quite
good", that's a bad, bad, bad thing. I'd much rather
take something reliably fast, than something that I have
to waste my time tweaking for.

Because then my binary may run really well on one uarch,
but two years down the line I will have wasted all my time
and need to tweak all over again for the next fragile piece
of crap.

Linus
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TopicPosted ByDate
Phoronix tests GCC compiler flags and Bulldozer.I.S.T.2012/04/19 03:05 AM
  Single page view?David Kanter2012/04/19 08:59 AM
    Single page view?wainwright2012/04/19 09:22 AM
    Single page view?slothrop2012/04/19 09:23 AM
      Single page view?David Kanter2012/04/19 09:31 AM
        Single page view?EduardoS2012/04/19 03:12 PM
    Is there a single page view option for RWT articles?anon2012/04/19 09:27 AM
    Single page view?Del2012/04/19 09:36 AM
      Single page view?slacker2012/04/19 03:56 PM
        Single page view?Del2012/04/22 06:09 AM
          Single page view?David Kanter2012/04/22 09:38 AM
            Single page view?Del2012/04/23 01:22 AM
    Single page view?Michael S2012/04/19 01:30 PM
      Single page view?Ungo2012/04/19 02:25 PM
        Single page view?Foo_2012/04/20 12:17 AM
          Single page view?James2012/04/20 04:01 AM
            There are ads on the web?JJB2012/04/20 04:32 AM
              What a bunch of freeloaders (NT)slacker2012/04/20 01:44 PM
                So are you, probablyiz2012/04/21 04:41 AM
                  Impression ad revenuePaul A. Clayton2012/04/21 06:44 AM
                  So are you, probablyslacker2012/04/21 01:09 PM
                    So are you, probablyDavid Kanter2012/04/22 09:41 AM
                      So are you, probablyiz2012/04/22 03:57 PM
                    So are you, probablyDoug Siebert2012/04/22 12:37 PM
                      Aha!David Kanter2012/04/22 03:45 PM
                        Aha!bakaneko2012/04/22 08:49 PM
                    So are you, probablyiz2012/04/22 03:48 PM
                      That's not how the business works...David Kanter2012/04/22 05:31 PM
                        That's not how the business works...iz2012/04/23 01:49 AM
                      So are you, probablyslacker2012/04/22 11:31 PM
                        back to phoronixMichael S2012/04/23 02:07 AM
                        So are you, probablyiz2012/04/23 03:29 AM
                          Membership at RWTDavid Kanter2012/04/23 11:24 AM
                          So are you, probablyJukka Larja2012/04/27 08:59 AM
  So, what do people think of these numbers>I.S.T.2012/04/19 07:34 PM
    So, what do people think of these numbers>Linus Torvalds2012/04/20 08:34 AM
      So, what do people think of these numbers>Kira2012/04/20 09:18 AM
        So, what do people think of these numbers>Linus Torvalds2012/04/20 10:05 AM
      So, what do people think of these numbers>Doug Siebert2012/04/20 09:00 PM
      So, what do people think of these numbers>Megol2012/04/21 09:05 AM
        So, what do people think of these numbers>Linus Torvalds2012/04/21 01:11 PM
          Most problems are fixed...Megol2012/04/24 07:00 AM
    So, what do people think of these numbers>bakaneko2012/04/20 11:16 AM
      So, what do people think of these numbers>bakaneko2012/04/20 11:37 AM
        So, what do people think of these numbers>Linus Torvalds2012/04/20 01:24 PM
          So, what do people think of these numbers>Joel2012/04/20 02:59 PM
            So, what do people think of these numbers>Kira2012/04/20 03:32 PM
              So, what do people think of these numbers>EduardoS2012/04/20 04:00 PM
                Bulldozer's Oddities.Joel2012/04/20 04:54 PM
                  In defense of Bulldozer's OdditiesDavid Kanter2012/04/20 05:32 PM
                    In defense of Bulldozer's OdditiesExophase2012/04/20 07:11 PM
                      In defense of Bulldozer's OdditiesEduardoS2012/04/20 07:46 PM
                        In defense of Bulldozer's OdditiesExophase2012/04/20 08:18 PM
                          In defense of Bulldozer's Odditiesanonymous2012/04/20 11:26 PM
                            In defense of Bulldozer's OdditiesJJB2012/04/20 11:34 PM
                              In defense of Bulldozer's Odditiesimaxx2012/04/21 07:21 AM
                                In defense of Bulldozer's OdditiesMichael S2012/04/21 10:42 AM
                                  Bulldozer's integer execution unitsDavid Kanter2012/04/25 04:29 PM
                                    Bulldozer's integer execution unitsExophase2012/04/26 12:17 PM
                                      Bulldozer's integer execution unitsanonymous2012/04/26 03:15 PM
                                        Bulldozer's integer execution unitsEduardoS2012/04/26 03:40 PM
                                          Bulldozer's integer execution unitsFoo_2012/04/27 08:21 AM
                                            Bulldozer's integer execution unitsMegol2012/04/27 01:38 PM
                                      Bulldozer's integer execution unitsEduardoS2012/04/26 03:47 PM
                                        Bulldozer's integer execution unitsExophase2012/04/26 05:02 PM
                                          Bulldozer's integer execution unitsEduardoS2012/04/26 06:03 PM
                                            Bulldozer's integer execution unitsExophase2012/04/26 06:24 PM
                                              Bulldozer's integer execution unitsEduardoS2012/04/26 07:18 PM
                                                Bulldozer's cache memory performanceHeikki Kultala2012/04/28 01:18 AM
                                                  Bulldozer's cache memory performanceEduardoS2012/04/28 10:06 AM
                                      Bulldozer's integer execution unitsDavid Kanter2012/04/26 04:03 PM
                                        Bulldozer's integer execution unitsExophase2012/04/26 04:59 PM
                                          Bulldozer's integer execution unitsDavid Kanter2012/04/26 10:53 PM
                                            Bulldozer's integer execution unitsExophase2012/04/27 08:42 AM
                                              Bulldozer's integer execution unitsDavid Kanter2012/04/27 11:06 AM
                                                Bulldozer's integer execution unitsEduardoS2012/04/27 01:27 PM
                                                K8 divided pipelines?Paul A. Clayton2012/04/27 01:59 PM
                                          Bulldozer's integer execution unitsMichael S2012/04/27 04:37 AM
                                            Bulldozer's integer execution unitsExophase2012/04/27 08:33 AM
                                            Bulldozer's integer execution unitsanonymous2012/04/27 09:03 AM
                                    Renaming FlagsKonrad Schwarz2012/04/27 03:04 AM
                                      Renaming Flagsnone2012/04/27 04:03 AM
                                        Renaming FlagsMegol2012/04/27 12:42 PM
                                    Bulldozer's integer execution unitshcl642012/04/27 04:31 PM
                                      VEX supports 3+ operands. FPU have renaming already(NT)Megol2012/04/28 08:20 AM
                              In defense of Bulldozer's OdditiesLinus Torvalds2012/04/21 12:26 PM
                                Thanks for the lessonJJB2012/04/21 02:23 PM
                                  Side note..Linus Torvalds2012/04/21 02:57 PM
                            In defense of Bulldozer's OdditiesExophase2012/04/21 12:13 PM
                            In defense of Bulldozer's OdditiesEduardoS2012/04/21 12:53 PM
                    In defense of Bulldozer's OdditiesGionatan Danti2012/04/21 12:42 PM
                    In defense of Bulldozer's Odditieshcl642012/04/27 05:07 PM
                      In defense of Bulldozer's OdditiesDavid Kanter2012/04/28 06:29 AM
                        In defense of Bulldozer's Odditieshcl642012/04/28 02:44 PM
                          In defense of Bulldozer's OdditiesDavid Kanter2012/04/28 09:42 PM
                            In defense of Bulldozer's Odditieshcl642012/04/28 10:39 PM
                  Bulldozer's Oddities.EduardoS2012/04/20 06:05 PM
                    Bulldozer's Oddities.anon2012/04/20 08:32 PM
                      Bulldozer's Oddities.EduardoS2012/04/21 12:37 PM
                        Bulldozer's Oddities.anon2012/04/21 10:16 PM
                          Bulldozer's Oddities.EduardoS2012/04/21 10:43 PM
                            Bulldozer's Oddities.anon2012/04/22 02:09 AM
                              Bulldozer's Oddities.EduardoS2012/04/22 01:57 PM
                                Bulldozer's Oddities.anon2012/04/22 04:17 PM
                                  Bulldozer's Oddities.EduardoS2012/04/22 05:05 PM
                                    Bulldozer's Oddities.anon2012/04/22 05:42 PM
                                      Bulldozer's Oddities.anon2012/04/22 06:01 PM
                                      Bulldozer's Oddities.EduardoS2012/04/22 10:28 PM
                                        Bulldozer's Oddities.anon2012/04/22 11:05 PM
                  Bulldozer's isn't bad.a reader2012/04/21 10:01 AM
                    Bulldozer's isn't bad.Kira2012/04/21 11:29 AM
                      Bulldozer's isn't bad.hcl642012/04/27 05:58 PM
                        Bulldozer's isn't bad.anon2012/04/27 06:16 PM
                          Bulldozer's isn't bad.hcl642012/04/27 07:33 PM
                            Bulldozer's isn't bad.rwessel2012/04/27 11:12 PM
                        Bulldozer's isn't bad.EduardoS2012/04/28 09:29 AM
                          Bulldozer's isn't bad.EduardoS2012/04/28 09:30 AM
                          Bulldozer's isn't bad.Michael S2012/04/28 12:36 PM
                    Bulldozer is made for SPEC fpPelle-482012/04/21 11:41 AM
                  Bulldozer's Oddities.mpx2012/04/22 03:47 AM
                    Bulldozer's Oddities.EduardoS2012/04/22 01:57 PM
                      Bulldozer's Oddities.mpx2012/04/23 07:04 AM
                        Bulldozer's Oddities.Eric2012/04/23 12:33 PM
                          Bulldozer's Oddities.EduardoS2012/04/23 02:22 PM
                            Bulldozer's Oddities.Eric2012/04/23 07:30 PM
                              Bulldozer's Oddities.hcl642012/04/27 06:16 PM
                            Bulldozer's Oddities.Y2012/04/25 04:34 AM
                              Bulldozer's IDIVHeikki Kultala2012/04/27 10:56 PM
                                Bulldozer's IDIVY2012/04/30 01:51 AM
                                  Bulldozer's IDIVEduardoS2012/04/30 05:39 AM
                                    Bulldozer's IDIVP3Dnow2012/05/08 01:23 AM
                                      Bulldozer's IDIVExophase2012/05/08 07:37 AM
                        Bulldozer's Oddities.EduardoS2012/04/23 02:15 PM
              Clustered MT as SMT for high frequencyPaul A. Clayton2012/04/20 04:10 PM
                Clustered MT as SMT for high frequencyhcl642012/04/28 12:56 AM
                  Clustered MT as SMT for high frequencyanonymous2012/04/28 01:43 AM
                    Clustered MT as SMT for high frequencyhcl642012/04/28 02:59 PM
                      Clustered MT as SMT for high frequencyanonymous2012/04/28 08:45 PM
                  Clustered MT as SMT for high frequencyanon2012/04/28 02:13 AM
                    Clustered MT as SMT for high frequencyhcl642012/04/28 03:23 PM
                      Clustered MT as SMT for high frequencyanon2012/04/28 06:19 PM
                        Clustered MT as SMT for high frequencyhcl642012/04/28 07:58 PM
                  Clustered MT as SMT for high frequencyDavid Kanter2012/04/28 06:38 AM
                    Guessed meaning of "strong dependency model"Paul A. Clayton2012/04/28 07:24 AM
                      Guessed meaning of "strong dependency model"EduardoS2012/04/28 09:46 AM
                        *Right meaning* about "strong dependency model"hcl642012/04/28 04:59 PM
                    Clustered MT as SMT for high frequencyhcl642012/04/28 04:24 PM
                      Clustered MT as SMT for high frequencyanonymous2012/04/28 08:50 PM
                        Clustered MT as SMT for high frequencyhcl642012/04/28 09:47 PM
                          SNB widthDavid Kanter2012/04/28 09:48 PM
                            SNB widthhcl642012/04/29 02:24 AM
                      Clustered MT as SMT for high frequencyDavid Kanter2012/04/28 09:56 PM
                        Clustered MT as SMT for high frequencyhcl642012/04/28 11:44 PM
                          SOI, FD vs. PDDavid Kanter2012/04/29 07:19 AM
                            SOI, FD vs. PDhcl642012/04/29 05:31 PM
                              SOI, FD vs. PDDavid Kanter2012/04/29 11:26 PM
                                SOI, FD vs. PDhcl642012/04/30 08:08 AM
                                  SOI, FD vs. PDDavid Kanter2012/04/30 09:59 AM
                                    SOI, FD vs. PDhcl642012/04/30 06:10 PM
                                      SOI, FD vs. PDDavid Kanter2012/04/30 06:32 PM
                                        SOI, FD vs. PDhcl642012/04/30 10:47 PM
                                          SOI, FD vs. PDDavid Kanter2012/05/01 02:24 AM
                                            SOI, FD vs. PDhcl642012/05/01 05:46 AM
                                            SOI, FD vs. PDhcl642012/05/01 06:37 AM
                                              SOI, FD vs. PDDavid Kanter2012/05/01 08:19 AM
                                          SOI, FD vs. PDhcl642012/05/01 07:39 AM
                                            PD-SOIDavid Kanter2012/05/02 12:22 PM
                                    SOI, FD vs. PDslacker2012/04/30 08:10 PM
                                      SOI, FD vs. PDDavid Kanter2012/04/30 10:16 PM
                                        SOI, FD vs. PDslacker2012/05/01 10:04 PM
                                          SOI, FD vs. PDDavid Kanter2012/05/02 08:19 AM
                                            SOI, FD vs. PDzou2012/05/02 12:23 PM
                  Previous discussion of clustered MTPaul A. Clayton2012/04/28 07:00 AM
                    Previous discussion of clustered MThcl642012/04/28 09:38 PM
                      Previous discussion of clustered MTDavid Kanter2012/04/30 04:37 PM
                        Previous discussion of clustered MThcl642012/04/30 07:24 PM
                          Previous discussion of clustered MTDavid Kanter2012/04/30 07:40 PM
                            Previous discussion of clustered MThcl642012/05/01 09:15 AM
                              Latency issuesDavid Kanter2012/05/02 12:01 PM
              So, what do people think of these numbers>Megol2012/04/21 01:57 AM
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