Sunny Cove wide

By: Seni (seniike.delete@this.hotmail.com), December 13, 2018 4:20 pm
Room: Moderated Discussions
Travis Downs (travis.downs.delete@this.gmail.com) on December 13, 2018 7:51 am wrote:
> Seni (seniike.delete@this.hotmail.com) on December 13, 2018 2:33 am wrote:
> > Travis Downs (travis.downs.delete@this.gmail.com) on December 12, 2018 8:25 pm wrote:
> > > Seni (seniike.delete@this.hotmail.com) on December 12, 2018 1:58 pm wrote:
> > > > -2nd store port. As far as x86 is concerned, this is (probably?) the only increase
> > > > in store ports that has ever occurred. It's unclear how important store port count
> > > > is to performance, since there is no precedent to base an estimate on.
> > > >
> > > >
> > > > -5-wide renamer. The wording I've seen is extremely vague and possibly misleading, but
> > > > it sounds like they increased the renamer from 4 work units to 5. A renamer work unit
> > > > is not the same as either an instruction or a uop, though, so a lot unresolved questions
> > > > here. There is no sign of a breakthrough renaming technique. Just wider.
> > >
> > > The work unit is "fused uop". I.e., something like an ALU ok with a memory-source operand
> > > counts as 1 for renaming, even though it will execute as two separate (unfused) uops.
> > >
> > > At least that has been the case going back to at least SNB.
> >
> > Are you certain that there have been no changes in the details
> > of what can be fused and where the fusion occurs?
>
> About Sunny Cove (let's just say Ice Lake?), no I have no idea. I was talking about existing chips.
>
> That is, when you said "A renamer work unit is not the same as either an instruction
> or a uop, though" I had thought you were talking about both the present and the
> future - i.e., that this "work unit" concept applied today as well.
>
> Today, we know what the work unit is: it's the fused uop [1]
>
> If I had to guess, it will be approximately the same in ICL. It's hard to see it getting worse,
> and it is also hard to see there being significantly more fusion, unless a new type of fusion is
> introduced. At most, I guess we'll get a reduction in the cases where delamination occurs.
>
>

>
> [1] Well, it's slightly more subtle than that, because there are two flavors of micro-fused uops: those
> that stay fused during allocation and those that don't (delamination) - and those details have changed from
> SNB to HSW to SKL (not sure about SKX). There are also register read limitations: the RAT can only handle
> so many registers per cycle - although it is hard to hit that limit w/o an artificial benchmark.

>

As a matter of nomenclature, I do rather like "renamer work unit" as it's clear and unambiguous about which pipeline stage this type of width is measured in, and does not imply any near-one-to-one relation to either instructions or uops.
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TopicPosted ByDate
Sunny Cove wideSeni2018/12/12 02:58 PM
  Sunny Cove wideTravis Downs2018/12/12 09:25 PM
    Sunny Cove wideJeff S.2018/12/12 10:26 PM
      Sunny Cove wideTravis Downs2018/12/13 08:42 AM
        Sunny Cove wideanon2018/12/13 09:09 AM
          Sunny Cove wideTravis Downs2018/12/13 09:30 AM
            Sunny Cove wideJeff S.2018/12/13 09:40 AM
              Sunny Cove wideTravis Downs2018/12/13 09:55 AM
                Sunny Cove wideJeff S.2018/12/13 12:41 PM
                  Sunny Cove wideTravis Downs2018/12/13 02:03 PM
                  Non-power-of-two set sizesPaul A. Clayton2018/12/15 07:30 PM
        Sunny Cove wideJeff S.2018/12/13 09:33 AM
          Sunny Cove wideTravis Downs2018/12/13 09:50 AM
          What is "u-tagged"?G Adair2018/12/13 09:54 PM
            What is "u-tagged"?Travis Downs2018/12/13 11:22 PM
            What is "u-tagged"?Jeff S.2018/12/14 08:48 AM
              What is "u-tagged"?anon2018/12/14 08:51 PM
                What is "u-tagged"?Jeff S.2018/12/14 10:23 PM
                  What is "u-tagged"?anon2018/12/15 05:37 AM
                    What is "u-tagged"?anon2018/12/15 08:06 AM
                      What is "u-tagged"?Travis Downs2018/12/15 09:52 AM
                        What is "u-tagged"?anon2018/12/16 08:26 AM
                          What is "u-tagged"?Anon2018/12/18 04:25 AM
    Sunny Cove wideSeni2018/12/13 03:33 AM
      Sunny Cove wideKevin G2018/12/13 08:37 AM
        Sunny Cove wideTravis Downs2018/12/13 09:17 AM
          Sunny Cove wideKevin G2018/12/17 10:09 AM
            Sunny Cove wideTravis Downs2018/12/18 03:14 PM
              Sunny Cove wideKevin G2018/12/19 12:02 PM
      Sunny Cove wideTravis Downs2018/12/13 08:51 AM
        Sunny Cove wideMaynard Handley2018/12/13 11:25 AM
          Sunny Cove wideTravis Downs2018/12/13 12:23 PM
            Sunny Cove wideanon2018/12/13 02:01 PM
              Sunny Cove wideTravis Downs2018/12/13 02:22 PM
                Sunny Cove wideanon2018/12/13 04:51 PM
                  Sunny Cove wideTravis Downs2018/12/13 05:36 PM
                    Sunny Cove wideanon2018/12/14 03:57 AM
                      Sunny Cove wideLinus Torvalds2018/12/14 01:54 PM
                        Sunny Cove wideanon2018/12/14 04:25 PM
                          Sunny Cove wideLinus Torvalds2018/12/14 06:46 PM
                            Sunny Cove wideanon2018/12/15 02:57 AM
                              Sunny Cove wideanon2018/12/15 05:59 AM
                                Sunny Cove wideanon2018/12/15 06:59 AM
                                  Sunny Cove wideanon2018/12/15 07:03 AM
                                Sunny Cove widea_different_anon2018/12/15 07:45 AM
                              Sunny Cove wideSeni2018/12/15 06:25 AM
                                Sunny Cove wideanon2018/12/15 07:02 AM
                                  Sunny Cove wideLinus Torvalds2018/12/15 10:52 AM
                                    Sunny Cove wideanon2018/12/15 11:13 AM
                                      Sunny Cove wideTravis Downs2018/12/16 11:15 AM
                                      Sunny Cove wideanon2018/12/17 12:42 AM
                                        how many anons here? (NT)Michael S2018/12/17 02:46 AM
                      Sunny Cove wideTravis Downs2018/12/15 10:08 AM
                        Sunny Cove wideanon2018/12/15 10:55 AM
                          Sunny Cove wideTravis Downs2018/12/16 09:19 AM
                            Sunny Cove wideanon2018/12/16 10:37 AM
                              Sunny Cove wideTravis Downs2018/12/16 10:57 AM
                                Sunny Cove wideanon2018/12/16 12:04 PM
                                  Sunny Cove wideTravis Downs2018/12/16 07:51 PM
                          Sunny Cove wideTravis Downs2018/12/16 11:32 AM
        Sunny Cove wideSeni2018/12/13 04:20 PM
          Fair enough! (NT)Travis Downs2018/12/13 04:43 PM
  Sunny Cove wide-.-2018/12/13 04:37 AM
    Sunny Cove wideanon2018/12/13 09:06 AM
      Sunny Cove wideTravis Downs2018/12/13 09:39 AM
        Sunny Cove wideanon2018/12/13 12:09 PM
          Sunny Cove wideTravis Downs2018/12/13 12:27 PM
            Sunny Cove wideanon2018/12/13 01:11 PM
    Sunny Cove wideTravis Downs2018/12/13 09:23 AM
      Sunny Cove wideanonymous22018/12/13 03:20 PM
        Sunny Cove wideTravis Downs2018/12/13 05:00 PM
          Sunny Cove wideanon³2018/12/13 10:34 PM
            Sunny Cove wideTravis Downs2018/12/16 07:53 PM
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