x86 and ARM

By: Maynard Handley (name99.delete@this.name99.org), November 26, 2020 1:05 pm
Room: Moderated Discussions
Chester (lamchester.delete@this.gmail.com) on November 26, 2020 10:29 am wrote:
> David Kanter (dkanter.delete@this.realworldtech.com) on November 22, 2020 11:01 pm wrote:
> > > > I think you need to look at what folks were saying at that time.
> > > >
> > > > For example, many people claim ARM has intrinsic advantages over x86. I was staking
> > > > out positions many didn't and don't agree with. Specifically, that ARM has no real
> > > > advantages over x86 for high performance cores (but does for small ones).
> > >
> > > Actually David if you look at the high performance Apple A13 vs Zen 2 (3950X) they have similar scores
> > > on GB5 and are on similar processes yet the A13 is much more power efficient, retaining the ARM advantage.
> > > Even with Zen 3 getting 23% higher scores on GB5 it is still in the same power efficiency ballpark as Zen
> > > 2. x86 just cannot approach the power efficiency of ARM at any processor core performance level.
> >
> > As others pointed out, comparing a desktop-focused chiplet to a
> > smartphone SoC makes for unrealistic power comparisons at best.
> >
> > Also, Geekbench isn't a good benchmark.
> >
> > Last, you should tell that to all the architects who have designed x86 and ARM processors.
> > They will tell you - for a high-performance core, there is very little difference. That includes
> > folks working (or previously working) at Apple, ARM, and many other companies.
> >
> > David
>
> https://tspace.library.utoronto.ca/bitstream/1807/80713/1/Wong_Henry_T_201711_PhD_thesis.pdf
> is a good read.
>
Surprisingly, modern ARM instruction sets are not much simpler than x86, despite being called “RISC”.
> The ARM instruction set also needs decoding into micro-ops. The ARM memory system is similar to x86, supporting
> unaligned data accesses and hardware TLB miss handling. Unlike x86, ARMv7 also allows predication of most instructions
> and an implicit barrel shift of one operand for most arithmetic instructions, which are features that are difficult
> to implement in out-of-order processors. On the other hand, one particularly complex-to-implement feature of
> x86 is variable instruction length where the length is non-trivial to compute (1 to 15 bytes), while ARM Thumb’s
> variable-length instructions only have two possible lengths (2 or 4 bytes).
> ...
> While x86 is more complex, the extra complexity due specifically to x86 is modest
> — much of the complexity of supporting an operating system (supporting exceptions,
> paging, privilege levels, etc.) is common to most instruction sets

>
> So yeah, X86 is more complex. But once you're designing a complex, OOO core that supports
> everything a modern OS demands, X86's extra complexity is a drop in the bucket.

Meanwhile, in the actually existing world (you know, the world of ARMv8 and people who have designed kickass systems using it)

https://twitter.com/Gok/status/1331848098931494915
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TopicPosted ByDate
David Kanter RWT article: "Why Apple Won’t ARM the MacBook"anon2020/11/19 07:17 PM
  David Kanter RWT article: "Why Apple Won’t ARM the MacBook"tarlinian2020/11/19 07:21 PM
  The article was spot on. Not possible in 2012-2014. Could become possible around 2016-2021.Jouni Osmala2020/11/19 10:29 PM
    The article was spot on. Not possible in 2012-2014. Could become possible around 2016-2021.anon2020/11/20 02:25 PM
  You're intellectually bankruptDaniel B2020/11/20 02:51 AM
    You're intellectually bankruptMichael S2020/11/20 05:22 AM
  David Kanter RWT article: "Why Apple Won’t ARM the MacBook"NaNon2020/11/20 04:08 AM
  He was right. ARM MBs weren't viable until 2019-2020, 8 years later (NT)JRB2020/11/20 08:34 AM
  David Kanter RWT article: "Why Apple Won’t ARM the MacBook"Rayla2020/11/20 09:37 AM
    David Kanter RWT article: "Why Apple Won’t ARM the MacBook"anon2020/11/20 02:26 PM
  David Kanter RWT article: "Why Apple Won’t ARM the MacBook"Jon Masters2020/11/20 10:24 AM
    David Kanter RWT article: "Why Apple Won’t ARM the MacBook"anon2020/11/20 02:31 PM
      David Kanter RWT article: "Why Apple Won’t ARM the MacBook"anon22020/11/20 04:57 PM
        David Kanter RWT article: "Why Apple Won’t ARM the MacBook"anon2020/11/20 09:29 PM
          David Kanter RWT article: "Why Apple Won’t ARM the MacBook"Jose2020/11/21 08:48 AM
    David Kanter RWT article: "Why Apple Won’t ARM the MacBook"anon22020/11/20 04:54 PM
      David Kanter RWT article: "Why Apple Won’t ARM the MacBook"Jan Vlietinck2020/11/20 11:23 PM
        David Kanter RWT article: "Why Apple Won’t ARM the MacBook"anon22020/11/21 12:41 AM
          David Kanter RWT article: "Why Apple Won’t ARM the MacBook"Jan Vlietinck2020/11/21 01:52 AM
            David Kanter RWT article: "Why Apple Won’t ARM the MacBook"anon22020/11/21 03:12 AM
              David Kanter RWT article: "Why Apple Won’t ARM the MacBook"Jan Vlietinck2020/11/21 03:25 AM
        Happy with my historical record :)David Kanter2020/11/21 09:30 AM
          Happy with my historical record :)Per Hesselgren2020/11/21 01:09 PM
            Happy with my historical record :)Maynard Handley2020/11/21 02:02 PM
              Happy with my historical record :)anon2020/11/22 12:23 AM
                Happy with my historical record :)anon22020/11/22 01:13 AM
                  Happy with my historical record :)Michael S2020/11/22 03:12 AM
                    Happy with my historical record :)anon2020/11/22 10:53 AM
                    Swift is 3-wide + custom layout (NT)vvid2020/11/23 04:59 AM
                      Swift is 3-wide + custom layoutanon2020/11/23 02:14 PM
                        No.Heikki Kultala2020/11/23 03:40 PM
                Happy with my historical record :)rwessel2020/11/22 09:14 AM
            Happy with my historical record :)David Kanter2020/11/21 02:51 PM
              Happy with my historical record :)Per Hesselgren2020/11/22 12:28 AM
                Happy with my historical record :)Dummond D. Slow2020/11/22 12:39 PM
                  Is ARM32 native in ARM64?Per Hesselgren2020/11/22 10:34 PM
                    Is ARM32 native in ARM64?Per Hesselgren2020/11/22 10:47 PM
                    Is ARM32 native in ARM64?vvid2020/11/23 06:48 AM
                      Is ARM32 native in ARM64?Per Hesselgren2020/11/23 07:15 AM
                        Is ARM32 native in ARM64?vvid2020/11/23 12:24 PM
                      Is ARM32 native in ARM64?Wilco2020/11/23 11:10 AM
                        Is ARM32 native in ARM64?vvid2020/11/23 01:21 PM
                          Is ARM32 native in ARM64?Per Hesselgren2020/11/23 01:54 PM
          Happy with my historical record :)anon2020/11/21 05:09 PM
            Happy with my historical record :)David Kanter2020/11/21 08:12 PM
          Happy with my historical record :)Emil Briggs2020/11/22 05:11 AM
          Happy with my historical record :)juanrga2020/11/22 08:22 AM
            Happy with my historical record :)Wilco2020/11/22 10:34 AM
              Happy with my historical record :)Dummond D. Slow2020/11/22 12:26 PM
                Happy with my historical record :)Dummond D. Slow2020/11/22 12:42 PM
          Happy with my historical record :) - but should you be?anon2020/11/22 02:35 PM
            Happy with my historical record :) - but should you be?anon.12020/11/22 03:42 PM
              Happy with my historical record :) - but should you be?Foo_2020/11/23 01:14 AM
                Happy with my historical record :) - but should you be?anon.12020/11/23 02:19 PM
            Happy with my historical record :) - but should you be?anon22020/11/22 04:24 PM
            Happy with my historical record :) - but should you be?David Kanter2020/11/22 11:01 PM
              Process technologyDavid Kanter2020/11/23 07:51 AM
                Process technologyDummond D. Slow2020/11/23 08:56 AM
                  Process technologyWilco2020/11/23 11:59 AM
                Process technologyDoug S2020/11/23 12:08 PM
                  Process technologyDummond D. Slow2020/11/23 12:24 PM
                  Process technologyDavid Kanter2020/11/23 05:17 PM
                    Process technologyDoug S2020/11/24 10:09 AM
                      Process technologyDavid Kanter2020/11/24 06:54 PM
              x86 and ARMChester2020/11/26 10:29 AM
                x86 and ARMMaynard Handley2020/11/26 01:05 PM
                x86 and ARMdmcq2020/11/26 02:31 PM
                  x86 and ARMChester2020/11/26 06:38 PM
                    x86 and ARMnone2020/11/27 12:07 AM
                      x86 and ARMJames2020/11/27 01:51 AM
                        x86 and ARMChester2020/11/27 05:22 PM
                          x86 and ARMMark Roulo2020/11/27 07:18 PM
                            x86 and ARMJames2020/11/28 03:22 AM
                            x86 and ARMWilco2020/11/28 06:54 AM
                              x86 and ARMSimon Farnsworth2020/11/30 02:20 AM
                            x86 and ARMgallier22020/11/29 11:42 PM
                          x86 and ARMWilco2020/11/28 06:46 AM
                            x86 and ARMChester2020/11/28 10:28 PM
                              and you don't understand the difference between 1995 and 2001 it seems (NT)anon2020/11/28 11:24 PM
                                sure, early 2000s thenChester2020/11/29 06:31 AM
                                Yes he doesHeikki Kultala2020/11/29 04:24 PM
                                  so not just any random binary (NT)anon2020/11/29 10:08 PM
                            x86 compatibility with 16-bit modesRob Thorpe2020/11/30 06:29 PM
                      x86 and ARMWilco2020/11/27 03:46 AM
                        x86 and ARMChester2020/11/28 10:46 PM
                          x86 and ARMJan Vlietinck2020/11/29 12:21 AM
                            x86 and ARMjuanrga2020/11/29 04:44 AM
                              x86 and ARMChester2020/11/29 06:30 AM
                                I didn't write that ARM is 7 times more efficient than x86. Don't make things up (NT)juanrga2020/11/29 08:04 AM
                                x86 and ARMDoug S2020/11/29 09:26 AM
                                  x86 and ARMwumpus2020/11/29 10:06 AM
                                  x86 and ARMDummond D. Slow2020/11/29 11:59 AM
                                    x86 and ARMjuanrga2020/11/30 01:28 AM
                                      x86 and ARMAdrian2020/11/30 04:50 AM
                                        x86 and ARMJan Vlietinck2020/11/30 06:04 AM
                                          x86 and ARMjuanrga2020/12/01 04:09 AM
                                        x86 and ARMDoug S2020/11/30 11:50 AM
                                      x86 and ARManon.12020/11/30 05:27 AM
                                        x86 and ARManon2020/11/30 08:33 PM
                                          x86 and ARManon.12020/12/01 07:11 AM
                                            x86 and ARManon2020/12/01 02:28 PM
                                              x86 and ARManon.12020/12/01 06:44 PM
                                      x86 and ARMDummond D. Slow2020/11/30 08:04 AM
                                      x86 and ARMGionatan Danti2020/11/30 08:44 AM
                                        x86 and ARMFoo_2020/12/01 12:26 AM
                                          x86 and ARMGionatan Danti2020/12/01 10:01 AM
                                        x86 and ARMjuanrga2020/12/01 04:17 AM
                    x86 and ARMUngo2020/11/27 01:55 AM
                    x86 and ARMjuanrga2020/11/27 03:58 AM
              Happy with my historical record :) - but should you be?anon2020/11/30 02:30 PM
                Happy with my historical record :) - but should you be?David Kanter2020/11/30 04:15 PM
                Happy with my historical record :) - but should you be?anon22020/12/01 03:22 AM
                  Happy with my historical record :) - but should you be?anon2020/12/01 02:16 PM
                    Happy with my historical record :) - but should you be?Maynard Handley2020/12/01 02:38 PM
                      Happy with my historical record :) - but should you be?Gabriele Svelto2020/12/08 07:51 AM
          Happy with my historical record :)Jan Vlietinck2020/11/23 12:55 AM
            Happy with my historical record :)anonymou52020/11/23 03:44 AM
              Happy with my historical record :)Jan Vlietinck2020/11/23 06:16 AM
                Happy with my historical record :)David Kanter2020/11/23 07:18 AM
                  Happy with my historical record :)Jan Vlietinck2020/11/23 09:37 AM
                  Happy with my historical record :)Ungo2020/11/23 08:48 PM
                  Happy with my historical record :)Maynard Handley2020/11/23 09:01 PM
                    Happy with my historical record :)Dummond D. Slow2020/11/24 07:48 AM
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