anon (anon.delete@this.anon.com) on June 3, 2013 8:54 am wrote:
>
> > Interesting slide from ARM at Computex shows 28nm A15 perf than
> > Silvermont at 22nm FF. Dispels Intel's Marketing FUD?
>
> http://www.pcworld.com/article/2040582/arm-claims-processor-superiority-over-intels-silvermont.html
>

I take Intel's marketing with a lot of salt but at least they have realistic access to real Cortex-A15 hardware. The same can't be said for ARM and Silvermont. Furthermore, most of Intel's claims come from comparing vs Saltwell, where they're more likely to do a fair test running the same binaries. ARM has nothing to go on but Intel's numbers which completely contradict their claims.

The power vs efficiency graph is completely insane if you ignore Silvermont and only look at Saltwell. First of all, how does Cortex-A7 even go up to Saltwell's performance when no one is clocking it beyond 1.2GHz vs up to 2GHz for Saltwell (in relevant plaforms, higher for desktops) and A7 is going to typically have considerably less perf/MHz than Saltwell. Yet ARM says A7 can deliver that same performance with 5x less power?

For reference, ~182mW @ 1.2GHz for Cortex-A7 on Samsung 28nm HKMG (http://beyond3d.com/showpost.php?p=1732331&postcount=530). Intel says for Saltwell 175mW for 600MHz, 500mW for 1.3GHz, and 750mW for 1.6GHz on what should be a competitive 32nm HKMG process (http://www.anandtech.com/show/5365/intels-medfield-atom-z2460-arrive-for-smartphones/2). Real power consumption numbers show that these estimates are fair.

Let's say A7 @ 1.2GHz is similar to Saltwell @ 1GHz, at least where the software is fairly level for both. A cubic fit shows that to be around 320mW. So Cortex-A7 is definitely more efficient here but nowhere close to 5x, and comes at a price of not being able to hit nearly as high peak performance.

I won't even touch on the Cortex-A15 part of the graph, which is probably more ridiculous.

I like ARM and I want them to succeed and be competitive, but this sort of marketing is just embarrassing..