N2, or V1?

By: Adrian (a.delete@this.acm.org), December 3, 2021 11:51 am
Room: Moderated Discussions
G (108106020.delete@this.nitt.edu) on December 3, 2021 9:25 am wrote:
> Adrian (a.delete@this.acm.org) on December 3, 2021 8:52 am wrote:
> > Adrian (a.delete@this.acm.org) on December 3, 2021 8:47 am wrote:
> > > Anon (no.delete@this.thanks.com) on December 3, 2021 6:52 am wrote:
> > > > Kara (karaardalan.delete@this.gmail.com) on December 3, 2021 6:36 am wrote:
> > > > > none (none.delete@this.none.com) on December 3, 2021 6:19 am wrote:
> > > > > > Kara (karaardalan.delete@this.gmail.com) on December 3, 2021 6:05 am wrote:
> > > > > > > Adrian (a.delete@this.acm.org) on December 3, 2021 5:51 am wrote:
> > > > > > > >
> > > > > > > > https://www.nextplatform.com/2021/12/02/aws-goes-wide-and-deep-with-graviton3-server-chip/
> > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > > The N2 is described much wider here than Arm has ever disclosed.
> > > > > > > I hate it when companies do this, like give some info what's gonna happen?
> > > > > >
> > > > > > What description of N2 is there in that article? I only see guesses.
> > > > >
> > > > > I meant the guesses, it's so not ARM to design 8 wide decode and 15 wide issue
> > > > > mArchs. 64kb l1i cache wouldn't be able to keep up Nor the punly ROBs, how
> > > > > do you feed such a wide core? Without smt or legendry l1i and rob?
> > > > >
> > > > > Neoverses are targeted toward server processors, making them wider doesn't make any sense.
> > > >
> > > > I thought that this was the V1 core? Aimed at maximum perf per thread.
> > >
> > >
> > > Amazon did not disclose which core they have used, but what was said matches better N2 than V1.
> > >
> > > Choosing N2 also makes more sense for Amazon, because they are more interested in
> > > general-purpose performance within a given power consumption than on performance
> > > when only few threads are active or performance for floating-point applications.
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> >
> >
> > Moreover, Graviton 3 uses 100 W for 64 cores.
> >
> > After subtracting uncore power, the power limit per core will be 1.25 W at most.
> >
> > This power level is below what a core from the X1/X2/V1 series requires, which is in the 2 ... 3 W range.
> >
> >
> > Power levels in the range 1 ... 1.5 W per core are the target for N1/N2.
> >
> > This is an additional reason to believe that Graviton 3 uses N2.
> >
> >
> >
> >
> >
> >
>
> I think Graviton3 uarch matches exactly with cortex-V1.
>
> https://i2.wp.com/semianalysis.com/wp-content/uploads/2021/12/7.jpg?w=2048&ssl=1
> https://images.anandtech.com/doci/16640/Neoverse_V1_13_575px.png


Some parts of the slides do indeed match well.

We do not know which are the customization options provided by ARM for V1.

From these slides, it looks like the core used in Graviton 3 is indeed based on V1, but with some parts deleted to lower the power consumption, e.g. with only half of the SVE datapath.

In that case the Graviton 3 cores, being slightly cut and used at a relatively low clock frequency, to be able to work within the 100 W TDP, should have intermediate performance and energy efficiency characteristics between an N2 and a V1 in maximum configuration.







< Previous Post in ThreadNext Post in Thread >
TopicPosted ByDate
Some info about the Amazon Graviton 3Adrian2021/12/03 06:51 AM
  Some info about the Amazon Graviton 3Kara2021/12/03 07:01 AM
    Some info about the Amazon Graviton 3---2021/12/03 10:03 AM
      Some info about the Amazon Graviton 3Kara2021/12/03 10:45 AM
  Some info about the Amazon Graviton 3Kara2021/12/03 07:05 AM
    Some info about the Amazon Graviton 3none2021/12/03 07:19 AM
      Some info about the Amazon Graviton 3Kara2021/12/03 07:36 AM
        N2, or V1? Anon2021/12/03 07:52 AM
          N2, or V1? Adrian2021/12/03 09:47 AM
            N2, or V1? Adrian2021/12/03 09:52 AM
              N2, or V1? G2021/12/03 10:25 AM
                N2, or V1? Adrian2021/12/03 11:51 AM
                  N2, or V1? Wilco2021/12/03 02:58 PM
                    N2, or V1? Adrian2021/12/04 03:33 AM
                      N2, or V1? -.-2021/12/04 04:37 AM
                      N2, or V1? Rayla2021/12/04 02:20 PM
                        N2, or V1? Adrian2021/12/05 01:15 AM
                          N2, or V1? dmcq2021/12/05 02:43 AM
                            N2, or V1? Adrian2021/12/05 03:54 AM
                              N2, or V1? ---2021/12/05 11:45 AM
                                N2, or V1? Adrian2021/12/05 01:07 PM
                                  Other (minor) power factors?Paul A. Clayton2021/12/06 07:37 AM
                    N2, or V1? Anon2021/12/04 10:53 PM
                      N2, or V1? Andrei F2021/12/05 04:22 AM
                Only 4 ALUsJörn Engel2021/12/03 07:37 PM
                  Only 4 ALUsWilco2021/12/04 09:54 AM
          N2, or V1? -.-2022/05/24 06:34 AM
            Graviton3 on Chip &CheesePer Hesselgren2022/06/17 06:19 AM
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