AVX-512 downclocking post

By: anon³ (nope.delete@this.example.test), January 17, 2020 1:25 am
Room: Moderated Discussions
Travis Downs (travis.downs.delete@this.gmail.com) on January 16, 2020 8:20 pm wrote:
> Here's a draft of a blog entry I'll post fully tomorrow:
>
> https://travisdowns.github.io/blog/2020/01/08/avxfreq.html
>
> Feedback, including frank feedback about things that are confusing or pointless, free
> proofreading, whatever is welcome. Reply here or by email or whatever you want.
>
> Please don't repost this anywhere other than RWT for the moment, that's for tomorrow.
>
> Ignore TODOs, I'll fix them tomorrow.

Impressive! (And I don't say that lightly.)

There are a couple of typos:

> We’ve got something to sink our teeth info!

s/info/into/

is the first one (I think). I will confess that I got through it once but I don't think I can make it through twice in one night to dig up where the others were :) It's dense but interesting reading, at least for the type of person who's been lurking around these parts for ages. Thanks for writing it up.

Though I will say that the endnotes bother me. I much prefer the style where hovering/tapping the reference number shows a popup with the text. It's akin to footnotes vs endnotes in printed material. But changing that would require messing with web tech, and I'd rather stick to my (hardware) day job, thank-you-very-much.


Back on topic: anyone know what happened to AMD's adaptive clocking (as used in Steamroller and described on the front page here)? I have seen no marketing material implying that it's in Zen/+/2, but I also haven't seen any analysis at this level of detail or finer for Zen. It seems like that scheme or a refined version would be a much more effective solution than Intel's brutish mess. A single heavy instruction burning 75,000 cycles (at 3GHz, 10us halted plus 10us gated down to 1/4 rate) seems... suboptimal.

I'm also a bit surprised at how long the Intel FIVR takes to slew (according to the numbers in the other thread plus your measured results). Sure, it's regulating truly massive currents going into gigantic capacitances (at least for the time scales involved), but my intuition would have been that a >100MHz controller could have done a bit better. But probably that's just me being thrown off by recently designing with CFB amplifiers that slew at over 1000V/us....
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TopicPosted ByDate
AVX-512 downclocking postTravis Downs2020/01/16 09:20 PM
  AVX-512 downclocking postanon³2020/01/17 01:25 AM
    AVX-512 downclocking postAndrei2020/01/17 02:47 AM
      AVX-512 downclocking postMontaray Jack2020/01/17 03:58 PM
        AVX-512 downclocking postAndrei2020/01/17 11:40 PM
          AVX-512 downclocking postMontaray Jack2020/01/19 02:10 AM
            AVX-512 downclocking postJan Olšan2020/01/19 01:01 PM
              AVX-512 downclocking postJan Olšan2020/01/19 01:11 PM
    AVX-512 downclocking postTravis Downs2020/01/17 02:59 PM
    AVX-512 downclocking postDavid Kanter2020/01/18 10:27 AM
      magnetic inductorsjokerman2020/01/18 08:03 PM
      AVX-512 downclocking postTravis Downs2020/01/24 11:36 AM
  AVX-512 downclocking postRay2020/01/17 02:22 AM
    AVX-512 downclocking postTravis Downs2020/01/17 01:10 PM
  AVX-512 downclocking postEtienne2020/01/17 03:16 AM
    Thanks, typos fixed and credited (NT)Travis Downs2020/01/17 01:15 PM
  Title suggestions welcome (NT)Travis Downs2020/01/17 08:54 AM
  AVX-512 downclocking postanonymou52020/01/17 10:53 AM
    AVX-512 downclocking postTravis Downs2020/01/17 11:14 AM
      AVX-512 downclocking postYoav2020/01/17 11:50 AM
        AVX-512 downclocking postTravis Downs2020/01/17 01:14 PM
      AVX-512 downclocking postanonymou52020/01/17 04:26 PM
        AVX-512 downclocking postTravis Downs2020/01/22 08:19 PM
          AVX-512 downclocking postanonymou52020/01/23 12:56 AM
            AVX-512 downclocking postFoyle2020/01/23 05:51 AM
              AVX-512 downclocking postanonymou52020/01/23 06:57 AM
                AVX-512 downclocking postTravis Downs2020/01/24 12:49 PM
            finer-grained licensesTravis Downs2020/01/24 01:03 PM
              finer-grained licensesanonymou52020/01/24 04:28 PM
                finer-grained licensesTravis Downs2020/01/25 09:46 AM
  post published (new line)Travis Downs2020/01/17 11:55 AM
    should say: (new LINK) (NT)Travis Downs2020/01/17 11:55 AM
      should say: (new LINK)Tim McCaffrey2020/01/17 01:44 PM
        Thanks, fixed and credited (NT)Travis Downs2020/01/17 02:54 PM
      should say: (new LINK)anon2020/01/17 09:12 PM
        should say: (new LINK)Travis Downs2020/01/22 03:28 PM
          Thanks!anon2020/01/22 08:06 PM
            Thanks!Travis Downs2020/01/22 08:16 PM
              Thanks!anon2020/01/22 10:20 PM
                Thanks!Travis Downs2020/01/23 01:51 AM
                  Thanks!Linus Torvalds2020/01/23 05:33 PM
                    Thanks!Travis Downs2020/01/24 12:44 PM
  Throttling dispatchGabriele Svelto2020/01/22 01:40 PM
    Itanium also used itDavid Kanter2020/01/22 02:04 PM
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