Maynard Handley (name99.delete@this.name99.org) on February 4, 2015 11:42 am wrote:
> Seni (seniike.delete@this.hotmail.com) on February 4, 2015 1:19 am wrote:
> > Ronald Maas (rmaas.delete@this.wiwo.nl) on February 3, 2015 8:23 pm wrote:
> > > Hugo Décharnes (hdecharn.delete@this.outlook.fr) on February 3, 2015 2:20 pm wrote:
> > > > Cortex-A57 delivers better performances than Cortex-A15, though their micro-architectures
> > > > are–nearly–identical. We'll see if ARM Ltd. reiterates with Cortex-A72.
> > >
> > > ARM's own web page about Cortex-A72 mentions 'major micro-architectural improvements'. This
> > > implies that the micro-architecture will be different compared to the Cortex-A15/A57.
> > >
> > > So guys. Any ideas what ARM could have do to make such an impressive performance
> > > improvement compared to A57? My pick (entirely speculative of cause):
> > >
> > > - 4 instruction decoder
> > > - memory disambiguation
> > > - 2 x 128-bit NEON execution units
> > >
> > > Ronald
> >
> > Most likely:
> >
> > - repipelined for ~30% higher frequency target
> > - more simd
> > - wider memory bus
> > - nothing else
>
> You don't think they'll at least add the ARMv8.1 RMW atomics? (Not that that changes performance
> substantially, but I imagine they want that part of the ISA to be universalized ASAP.)

If they did, it wouldn't count as a major microarchitectural improvement, because it's not microarchitectural at all. It's just architectural.