Comparing A9 and Skylake

By: David Kanter (dkanter.delete@this.realworldtech.com), March 13, 2016 6:15 pm
Room: Moderated Discussions
Maynard Handley (name99.delete@this.name99.org) on March 13, 2016 2:39 pm wrote:
> Alberto (git.delete@this.git.it) on March 12, 2016 2:04 pm wrote:
> > Heikki Kultala (hkultala.delete@this.iki.fi) on March 12, 2016 4:37 am wrote:
> > > Ricardo B (ricardo.b.delete@this.xxxxx.xx) on March 10, 2016 9:35 am wrote:
> > > > Doug S (foo.delete@this.bar.bar) on March 10, 2016 8:03 am wrote:
> > > > > Ricardo B (ricardo.b.delete@this.xxxxx.xx) on March 9, 2016 4:05 pm wrote:
> > > > > > Eg, Apple's A9 core seems to be almost as big as a Skylake core.
> > > > >
> > > > >
> > > > > Measured on what basis? The A9 SoC includes a lot of stuff Skylake doesn't. If you are talking about
> > > > > just the core, where is your demarcation point for what is considered the core? Is cache included,
> > > > > and if so up to what level? How do you account for differences in transistor choices? (i.e. since
> > > >
> > > > Based on available die analysis, Skylake core including
> > > > L2 is ~8.7 mm^2 and A9 cores including L2 is ~6.8 mm^2.
> > >
> > > This is not a very good comparison, as
> > > 1) Skylake has small L2 caches and always uses L3 cache, but Apple A9 has big L2 cache and
> > > works very well without L3 cache. Better comparison would be to include only L1 caches.
> > >
> > > 2) Intels "14nm" process is considerably denser than TSMC "16nm" process
> >
> > If you consider that Skylake core has powerful SSE and AVX units that accounts an intersting
> > portion of the die and they are absent on A9 footprint, also we have a lot of other hardware implemented
> > features like virtualization, VPro, turbo management, SMT governor, TSX, AES, MPX and so on.
> > So the comparison done is not idiotic at all.
> > Another variable is that Skylake core is on Intel LP process and not on high density libraries,
> > like is A9, so the difference accounted from the different processes is virtually nullified. Moreover
> > Skylake footprint is very relaxed to allow an easy turbo clock with steady clock speeds.
>
> An ARMv8 core is supposed to include virtualization. Of course it's possible that
> Apple simply didn't bother to implement that because they decided they won't need
> it over the expected lifespan of this design --- I honestly don't know.

Honestly I think the comparison would be more constructive if someone had a breakdown of area for SKL and the Twister cores (e.g., actual L2 cache size, etc.). Things like VPro probably don't impact the core much. But TSX, etc. do.

I think it's pretty clear that Apple's core is quite aggressive and fairly impressive. It doesn't have nearly the same range as Intel, but it's leagues better than other cores.

David
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TopicPosted ByDate
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    X-Gene 3 power enelopecanon2016/03/09 09:32 AM
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            bad size comparison between Apple A9 and skylake coresHeikki Kultala2016/03/12 05:37 AM
              bad size comparison between Apple A9 and skylake coresAlberto2016/03/12 02:04 PM
                bad size comparison between Apple A9 and skylake coresMaynard Handley2016/03/13 02:39 PM
                  bad size comparison between Apple A9 and skylake coresDoug S2016/03/13 06:10 PM
                  Comparing A9 and SkylakeDavid Kanter2016/03/13 06:15 PM
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                      Core sizes & performanceDavid Kanter2016/03/14 09:16 AM
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        Common wisdom??Paul A. Clayton2016/03/10 09:33 AM
          Common wisdom??Ricardo B2016/03/10 10:49 AM
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