To elaborate

By: David Kanter (dkanter.delete@this.realworldtech.com), July 12, 2020 7:22 pm
Room: Moderated Discussions
David Kanter (dkanter.delete@this.realworldtech.com) on July 12, 2020 8:20 pm wrote:
> Travis Downs (travis.downs.delete@this.gmail.com) on July 12, 2020 8:03 pm wrote:
> > David Kanter (dkanter.delete@this.realworldtech.com) on July 12, 2020 6:13 pm wrote:
> > > I did some analysis a while back that might useful to share here.
> > >
> > > 8.0 mm2 SKL core
> > > 0.9 mm2 AVX512
> > > 2.0 mm2 1MB L2$
> > > 2.4 mm2 1.375MB L3$
> > > 0.4 mm2 Snoop filter
> > > 2.0 mm2 caching and home agent
> > > 2.2 mm2 FIVR, PLLs
> > > 0.4 mm2 Mystery block
> > >
> > > 18.0 mm2 Total SKL-SP tile
> > >
> > > So AVX512 is about 5% of the tile area, the tiles are 72% of the total area of SKL-SP.
> > >
> > > If you removed AVX512 you'd save 28mm2 for the whole chip, which would let you add at most 2 tiles.
> > >
> > > In that vein, it seems like a pretty reasonable trade-off.
> >
> > Hmm, you read my mind, I was just wandering over to see if someone had done something like this.
>
> A long time ago I did the analysis for a ton of this stuff.
>
> > Do you have anything for BDW?
>
> Nope.
>
> > Another way of approaching the full cost of AVX-512 would be to look
> > at the BDW-SKL delta. Obviously there were other changes in SKL that may have increased area, but
> > not that many, and BDW is the same process so this could upper-bound the AVX2->AVX-512 cost.
>
> There were a lot of changes in BDW-->SKL. I suspect this analysis wouldn't be as fruitful.

The other thing to consider is that many of the SKL microarchitectural choices might be tied to AVX512. E.g., banking/porting in the L1D.

David
< Previous Post in ThreadNext Post in Thread >
TopicPosted ByDate
Skylake-SP area breakdownDavid Kanter2020/07/12 05:13 PM
  Skylake-SP area breakdownanon22020/07/12 06:01 PM
    Skylake-SP area breakdownTravis Downs2020/07/12 07:02 PM
      Skylake-SP area breakdownanon2020/07/12 07:44 PM
  Skylake-SP area breakdownTravis Downs2020/07/12 07:03 PM
    Skylake-SP area breakdownDavid Kanter2020/07/12 07:20 PM
      To elaborateDavid Kanter2020/07/12 07:22 PM
        To elaborateTravis Downs2020/07/13 06:03 AM
          To elaborateAnon2020/07/13 06:36 AM
            To elaborateAdrian2020/07/13 12:45 PM
              To elaborateAnon2020/07/13 01:06 PM
                To elaborateChester2020/07/13 07:30 PM
  Alternatives ImplementationsKyle Siefring2020/07/13 05:02 PM
    Alternatives ImplementationsTravis Downs2020/07/13 07:41 PM
    Alternatives ImplementationsMaynard Handley2020/07/13 09:37 PM
      Alternatives ImplementationsDoug S2020/07/13 10:25 PM
        Mask costsDavid Kanter2020/07/14 07:13 AM
        Alternatives Implementationstarlinian2020/07/14 07:22 AM
          Alternatives ImplementationsDoug S2020/07/14 09:03 AM
          Alternatives ImplementationsMaynard Handley2020/07/14 09:12 AM
        Alternatives ImplementationsMaynard Handley2020/07/14 09:10 AM
          Alternatives ImplementationsDoug S2020/07/14 09:47 AM
            Alternatives ImplementationsBrett2020/07/14 12:38 PM
            Alternatives Implementationstarlinian2020/07/14 01:30 PM
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