By: Wilco (Wilco.Dijkstra.delete@this.ntlworld.com), February 4, 2015 3:01 pm
Room: Moderated Discussions
juanrga (nospam.delete@this.juanrga.com) on February 4, 2015 5:23 am wrote:
> Wilco (Wilco.Dijkstra.delete@this.ntlworld.com) on February 4, 2015 1:58 am wrote:
> > juanrga (nospam.delete@this.juanrga.com) on February 3, 2015 5:15 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.
> > >
> > > More than 80% performance gains over A57.
> >
> > ... but it was clearly stated that this is at the same mobile power
> > budget. So the gains are from improved power efficiency.
> >
> > > ~50% IPC gain over A57, rest from ~30% higher clocks.
> >
> > I didn't read anything that indicated such a huge IPC gain. Peak performance should be much better of
> > course, but much of that will be due to higher frequencies enabled by the improved power efficiency.
> >
> > Wilco
> >
> >
>
> I did read the preliminary analysis here
>
> http://techreport.com/news/27767/arm-unveils-cortex-a72-cpu-mali-t880-graphics-and-more
That analysis is wrong, ignoring the fact that the comparison is at identical power, not at max frequency. The large gain in power efficiency allows the A72 to run at a higher frequency than A57 or A15, even on the same process. That means the 80% benefit is split between frequency gains enabled by lower power on the same process, frequency gains due to FinFet and IPC gains. Let's say the average IPC gain is 20% (probably not far off given the range Peter mentioned), so that means the frequency gain is 50% (1.5 * 1.2 = 1.8, something else Techreport got wrong).
Wilco
> Wilco (Wilco.Dijkstra.delete@this.ntlworld.com) on February 4, 2015 1:58 am wrote:
> > juanrga (nospam.delete@this.juanrga.com) on February 3, 2015 5:15 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.
> > >
> > > More than 80% performance gains over A57.
> >
> > ... but it was clearly stated that this is at the same mobile power
> > budget. So the gains are from improved power efficiency.
> >
> > > ~50% IPC gain over A57, rest from ~30% higher clocks.
> >
> > I didn't read anything that indicated such a huge IPC gain. Peak performance should be much better of
> > course, but much of that will be due to higher frequencies enabled by the improved power efficiency.
> >
> > Wilco
> >
> >
>
> I did read the preliminary analysis here
>
> http://techreport.com/news/27767/arm-unveils-cortex-a72-cpu-mali-t880-graphics-and-more
That analysis is wrong, ignoring the fact that the comparison is at identical power, not at max frequency. The large gain in power efficiency allows the A72 to run at a higher frequency than A57 or A15, even on the same process. That means the 80% benefit is split between frequency gains enabled by lower power on the same process, frequency gains due to FinFet and IPC gains. Let's say the average IPC gain is 20% (probably not far off given the range Peter mentioned), so that means the frequency gain is 50% (1.5 * 1.2 = 1.8, something else Techreport got wrong).
Wilco
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 |