Zen 3

By: hobold (hobold.delete@this.vectorizer.org), October 11, 2020 1:22 pm
Room: Moderated Discussions
anon (anon.delete@this.ymous.org) on October 11, 2020 1:07 pm wrote:
[...]
> What difference do you make between "unseen before" and "unknown"?

I am not sure if I can come up on the spot with a proper definition, but maybe two examples can illustrate the difference (and a third example will illustrate the difficulty of defining things).

1. The stream prefetcher mentioned before requires very little information: a current address and a stride. This information completely determines the next and all future addresses that will be (pre-)fetched. So those addresses are known, but still unseen by, say, some physical probe on some physical address bus. The pattern is easy to predict, and there are practical computational shortcuts to find, say, the seventh address from now (without needing to compute the six addresses inbetween).

2. Unknowable, in contrast, are chaotic things like Newton's three body problem, or the double pendulum, or the weather. One can argue that the information content here is infinite, as real numbers describing the system's state require unlimited precision. The future configuration of such a system, beyond a brief window of short term immediate future, is unknown.

3. The grey area is something like a picture of the Mandelbrot set. You give the computer a finite set of parameters and let it churn out pixels (using finite precision). The final picture is entirely determined by the parameters. However, certain parts of the resulting picture cannot be guessed beforehand, other than actually performing the full chain of computations. There are no general shortcuts, there is no method of prediction that could save work on all pixels. Many clever optimizations have been devised, and many pixels can be accurately generated with less effort. But not all. So are these problematic pixels known or unknown beforehand? They are fully determined from the start. On the other hand they are not predictable (in the sense of saving effort to obtain them, one cannot "skip ahead" to them).
< Previous Post in ThreadNext Post in Thread >
TopicPosted ByDate
Zen 3Blue2020/10/08 08:58 AM
  Zen 3Rayla2020/10/08 09:10 AM
  Zen 3Adrian2020/10/08 09:13 AM
    Does anyone know whether Zen 3 has AVX-512? (NT)Foo_2020/10/08 10:54 AM
      Does anyone know whether Zen 3 has AVX-512?Adrian2020/10/08 11:11 AM
  Zen 3 - Number of load/store units2020/10/08 09:21 AM
    Zen 3 - Number of load/store unitsRayla2020/10/08 09:28 AM
      Zen 3 - Number of load/store units2020/10/08 10:22 AM
        Zen 3 - Number of load/store unitsAdrian2020/10/08 10:53 AM
          Zen 3 - Number of load/store unitsTravis Downs2020/10/08 08:45 PM
          Zen 3 - CAD benchmarkPer Hesselgren2020/10/09 06:29 AM
            Zen 3 - CAD benchmarkAdrian2020/10/09 08:27 AM
        Zen 3 - Number of load/store unitsitsmydamnation2020/10/08 01:38 PM
          Zen 3 - Number of load/store unitsGroo2020/10/08 01:48 PM
            Zen 3 - Number of load/store unitsWilco2020/10/08 02:02 PM
              Zen 3 - Number of load/store unitsDummond D. Slow2020/10/08 03:39 PM
                Zen 3 - Number of load/store unitsDoug S2020/10/09 07:11 AM
                  Zen 3 - Number of load/store unitsDummond D. Slow2020/10/09 08:43 AM
                    Zen 3 - Number of load/store unitsDoug S2020/10/09 12:43 PM
                      N7 and N7P are not load/Store units - please fix the topic in your replies (NT)Heikki Kultala2020/10/10 06:37 AM
  Zen 3Jeff S.2020/10/08 11:16 AM
    Zen 3anon2020/10/08 12:57 PM
    Disappointing opening line in paperPaul A. Clayton2020/10/11 05:16 AM
      Thoughts on "Improving the Utilization of µop Caches..."Paul A. Clayton2020/10/14 11:11 AM
        Thoughts on "Improving the Utilization of µop Caches..."anon2020/10/15 10:56 AM
          Thoughts on "Improving the Utilization of µop Caches..."anon2020/10/15 10:57 AM
            Sorry about the messanon2020/10/15 10:58 AM
              Sorry about the messBrett2020/10/16 02:22 AM
          Caching dependence info in µop cachePaul A. Clayton2020/10/16 05:20 AM
            Caching dependence info in µop cacheanon2020/10/16 11:36 AM
              Caching dependence info in µop cachePaul A. Clayton2020/10/18 12:28 PM
  Zen 3juanrga2020/10/09 09:12 AM
  Zen 3Mr. Camel2020/10/09 05:30 PM
    Zen 3anon.12020/10/09 11:44 PM
      Cinebench is terrible benchmarkDavid Kanter2020/10/10 09:36 AM
        Cinebench is terrible benchmarkanon.12020/10/10 11:06 AM
        Cinebench is terrible benchmarkhobold2020/10/10 11:33 AM
          Some comments on benchmarksPaul A. Clayton2020/10/14 11:11 AM
            Some comments on benchmarksMark Roulo2020/10/14 02:21 PM
    Zen 3Adrian2020/10/10 12:59 AM
      Zen 3Adrian2020/10/10 01:18 AM
        Zen 3majord2020/10/15 03:02 AM
  Zen 3hobold2020/10/10 07:58 AM
    Zen 3Maynard Handley2020/10/10 09:36 AM
      Zen 3hobold2020/10/10 11:19 AM
        Zen 3anon2020/10/11 01:58 AM
          Zen 3hobold2020/10/11 11:32 AM
            Zen 3anon2020/10/11 12:07 PM
              Zen 3hobold2020/10/11 01:22 PM
    Zen 3anon2020/10/10 10:51 AM
    Zen 3Michael S2020/10/11 12:16 AM
      Zen 3hobold2020/10/11 01:13 AM
        Zen 3Michael S2020/10/11 01:18 AM
      Zen 3anon.12020/10/11 11:17 AM
  Zen 3David Hess2020/10/12 05:43 AM
    more power? (NT)anonymous22020/10/12 12:26 PM
      I think he's comparing 65W 3700X vs 105W 5800X (NT)John H2020/10/12 03:33 PM
        ?! Those are apples and oranges! (NT)anon2020/10/12 03:49 PM
Reply to this Topic
Name:
Email:
Topic:
Body: No Text
How do you spell avocado?