AVX-512 downclocking post

By: Travis Downs (travis.downs.delete@this.gmail.com), January 17, 2020 1:10 pm
Room: Moderated Discussions
Ray (no.delete@this.thanks.com) on January 17, 2020 1:22 am wrote:
> 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.
> Can I make a small request to not name things "Type 1", "Type 2" etc. I hope it's not just me, but
> I am completely incapable of remembering things by number. I'll have to click back to your definition
> pretty much every time you use it. Please use even something vaguely descriptive before that. My
> brain just doesn't work that way, and maybe there are other people that are the same.

I changed this, but man it was a bit painful.

I went with "voltage" or "voltage-only" for Type 1 and "frequency" for Type 2.

> Suggestions:
> 1) I would suggest "Pre-downshift", "Downshift halt", "Post-downshift",
> "Upshift halt", and "Post-upshift" as names for regions.
> 2) It might be interesting to have a graph of IPC*Frequency, so it's trivial
> to see how much the combination of decreased/increased IPC and decreased/increased
> frequency are affecting actual effective processing capability.

It turns out not to be very interesting, because we are never really running the same workload at low and high frequencies, except for the 4x throttling thing. So yeah, if you are running 4x slower, the small 3.2 / 2.8 = ~14% frequency boost barely makes a dent, so the IPC graph looks the same as the IPC * freq graph, basically.

I do actually show what you want in the voltage section: when I show paytime (payload time), that's wall-clcok time (rdtsc cycles), so it is effectively ipc * frequency.

> 3) Please use an alpha of around 0.5 or so for your lines. It makes it much easier
> to figure out what is going on when they overlap. If you want, perhaps increase
> the alpha of the most important line a bit, and decrease the others.

I used some alpha now for the zoomed out charts, although I have my doubts it makes it much better? The zoomed in ones I think are clear enough because the noise and spread spectrum clocking tend to make the lines not totally overlapping.

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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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