By: anon (anon.delete@this.anon.com), February 4, 2015 5:19 am
Room: Moderated Discussions
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
Would its IPC actually warrant a 4 wide decoder yet? Such a thing should not improve energy efficiency.
> - memory disambiguation
Memory disambiguation also does not seem like it would improve efficiency much. It increases the amount of speculation that can be done, which can increase performance of course, but improve perf/watt? I think IBM only implemented this with POWER8, and they haven't been ones to shy away from micro architectural complexity.
I would say perhaps improved branch prediction, reorganized cache design, and improved hardware prefetching.
I think the L2 cache might be brought in and be integrated with the core design as it is with other high performance CPUs. With a more modular and configurable L3 cache shared within the cluster. The low associativity L1 and large shared modular L2 seems like a potential problem to me.
> - 2 x 128-bit NEON execution units
>
> Ronald
> 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
Would its IPC actually warrant a 4 wide decoder yet? Such a thing should not improve energy efficiency.
> - memory disambiguation
Memory disambiguation also does not seem like it would improve efficiency much. It increases the amount of speculation that can be done, which can increase performance of course, but improve perf/watt? I think IBM only implemented this with POWER8, and they haven't been ones to shy away from micro architectural complexity.
I would say perhaps improved branch prediction, reorganized cache design, and improved hardware prefetching.
I think the L2 cache might be brought in and be integrated with the core design as it is with other high performance CPUs. With a more modular and configurable L3 cache shared within the cluster. The low associativity L1 and large shared modular L2 seems like a potential problem to me.
> - 2 x 128-bit NEON execution units
>
> Ronald
Topic | Posted By | Date |
---|---|---|
ARM announces A72 | Maynard Handley | 2015/02/03 11:36 AM |
ARM announces A72 | anon | 2015/02/03 12:53 PM |
ARM announces A72 | Hugo Décharnes | 2015/02/03 01:20 PM |
ARM announces A72 | juanrga | 2015/02/03 04:15 PM |
ARM announces A72 | Wilco | 2015/02/04 12:58 AM |
ARM announces A72 | Eric Bron | 2015/02/04 01:48 AM |
ARM announces A72 | none | 2015/02/04 02:24 AM |
ARM announces A72 | Eric Bron | 2015/02/04 02:42 AM |
ARM announces A72 | Exophase | 2015/02/04 07:01 AM |
ARM announces A72 | Anon | 2015/02/04 07:35 AM |
ARM announces A72 | Exophase | 2015/02/04 07:58 AM |
ARM announces A72 | Groo | 2015/02/04 09:24 AM |
ARM Marketing, BS up to my ears | David Kanter | 2015/02/04 10:51 AM |
ARM Marketing, BS up to my ears | Maynard Handley | 2015/02/04 01:59 PM |
ARM Marketing, BS up to my ears | David Kanter | 2015/02/04 02:21 PM |
ARM Marketing, BS up to my ears | Groo | 2015/02/04 02:30 PM |
ARM announces A72 | juanrga | 2015/02/04 04:23 AM |
ARM announces A72 | Wilco | 2015/02/04 03:01 PM |
ARM announces A72 | juanrga | 2015/02/04 04:06 PM |
ARM announces A72 | Anon | 2015/02/04 01:28 AM |
ARM announces A72 | juanrga | 2015/02/04 04:31 AM |
ARM announces A72 | Aaron Spink | 2015/02/04 06:49 AM |
ARM announces A72 | Ronald Maas | 2015/02/03 07:23 PM |
ARM announces A72 | Seni | 2015/02/04 12:19 AM |
ARM announces A72 | Maynard Handley | 2015/02/04 10:42 AM |
ARM announces A72 | Seni | 2015/02/04 12:33 PM |
ARM announces A72 | dmcq | 2015/02/04 12:57 PM |
ARM announces A72 | Ronald Maas | 2015/02/04 06:42 PM |
ARM announces A72 | anon | 2015/02/04 05:19 AM |
ARM announces A72 | Exophase | 2015/02/04 07:31 AM |
ARM announces A72 | David Kanter | 2015/02/04 10:25 AM |
ARM announces A72 | Exophase | 2015/02/04 01:33 PM |
ARM announces A72 | anon | 2015/02/04 10:27 PM |
ARM announces A72 (fixed format) | anon | 2015/02/04 10:29 PM |
ARM announces A72 | Exophase | 2015/02/04 11:11 PM |
ARM announces A72 | anon | 2015/02/05 12:02 AM |
ARM announces A72 | anon | 2015/02/04 05:57 PM |
ARM announces A72 | Wilco | 2015/02/03 01:39 PM |
ARM announces A72 | Maynard Handley | 2015/02/03 02:13 PM |
ARM announces A72 | anon | 2015/02/03 02:29 PM |
ARM announces A72 | Wilco | 2015/02/03 02:44 PM |
ARM announces A72 | David Kanter | 2015/02/04 09:56 AM |
ARM announces A72 | Peter Greenhalgh | 2015/02/04 10:56 AM |
ARM announces A72 | Aaron Spink | 2015/02/04 11:59 AM |
ARM announces A72 | Alberto | 2015/02/07 10:22 AM |
ARM announces A72 | Exophase | 2015/02/07 10:47 AM |
ARM announces A72 | Alberto | 2015/02/07 12:44 PM |
ARM announces A72 | Exophase | 2015/02/07 02:35 PM |
ARM announces A72 | Alberto | 2015/02/08 01:09 AM |
ARM announces A72 | Exophase | 2015/02/08 11:05 AM |
ARM announces A72 | David Kanter | 2015/02/08 12:39 AM |
ARM announces A72 | dmcq | 2015/02/08 04:14 AM |
ARM announces A72 | Michael S | 2015/02/08 04:38 AM |
ARM announces A72 | Gabriele Svelto | 2015/02/10 05:11 AM |
ARM announces A72 | Jouni Osmala | 2015/02/10 11:24 AM |
slit vs unified | Michael S | 2015/02/10 01:57 PM |
slit vs unified | dmcq | 2015/02/11 05:44 AM |
ARM announces A72 | Doug S | 2015/02/08 09:00 AM |
ARM announces A72 | Exophase | 2015/02/08 10:57 AM |
ARM announces A72 | dmcq | 2015/02/04 01:10 PM |
ARM announces A72 | David Kanter | 2015/02/04 02:28 PM |
ARM announces A72 | Wilco | 2015/02/04 01:59 PM |
ARM announces A72 | Aaron Spink | 2015/02/04 09:31 PM |
Intel 32nm vs 14 nm | Michael S | 2015/02/05 01:03 AM |
Intel 32nm vs 14 nm | Wilco | 2015/02/05 02:27 AM |
Intel 32nm vs 14 nm | David Kanter | 2015/02/05 09:05 AM |
Intel 32nm vs 14 nm | carop | 2015/02/05 11:12 AM |
Normalize to drawn or effective width? | David Kanter | 2015/02/05 11:45 AM |
Normalize to drawn or effective width? | carop | 2015/02/05 02:40 PM |
Normalize to drawn or effective width? | David Kanter | 2015/02/06 12:44 PM |