I looked up the figures AMD has posted for Steamroller (over PD) and Excavator (over SR) and the quoted figures / the used phrases seem to vary depending on to whom the information is intended to. Even when we are talking about the exactly same time period :sneaky:
In the NDA version of "AMD 2014 A-SERIES INTRODUCTION" sheet
(1), dated to January 2014 AMD says:
"Up to 20% IPC uplift (average ~10%) on up to 4 Steamroller CPU Cores."
In the public version of the same sheet
(2) they simply say
"Up to 20% IPC uplift on up to 4 Steamroller CPU Cores."
In the NDA version of "Tech Day 2015" slide
(3) AMD says 4-15% higher IPC over Steamroller. In the ISSCC 2015 Excavator presentation
(4) the figure is said to be 5%.
Since Lisa Su didn't specify Excavator by the name
, it is pretty apparent that the
"greater than 40% IPC uplift" expected by AMD is not over Excavator, but over Piledriver or Steamroller designs.
"Our Zen based CPU development is on track to achieve greater than 40% IPC uplift from our previous generation and we're on schedule to sample later this year.
01/19/2016 - Lisa Su (Earnings Confrence Call)
When Excavator is specified by the name, the quoted figures are lower every time:
40% more instructions per clock*.
*Based on internal AMD estimates for “Zen” x86 CPU core compared to “Excavator” x86 CPU core.
05/06/2015 - Mark Papermaster (2015 Financial Analyst Day - Foundation For The Future PPT/PDF)
Both Piledriver and Steamroller are available for desktop and server segments, while Excavator is not available in either segment (so far mobile only). Despite the name the Steamroller based Opterons were never a real server CPUs, unlike Bulldozer & Piledriver (Orochi) were. Just like Orochi die, the Zeppelin die is inteded purely for servers and desktops. Is it possible that AMD just "accidentally" happened to plot both Zeppelin and Orochi die to the same (unlabeled chart) in the "investor presentation sheet" dated to May 2016, I think not :sneaky: Orochi can mean either the o.g Bulldozer (Orochi Rev. B) or Piledriver (Orochi Rev. C), however Piledriver is the only Orochi based design still shipping (i.e current generation core).
"Greater than 40% IPC uplift" can obviously mean anything higher than 40%, however I think practically we are talking about anything between 40.1 - 49.9%. I would also imagine that if the expected IPC uplift was e.g. 51.1% AMD would use "greater than 50% IPC uplift" term instead of making an understatement to hold back the expectations.
According to AMD Steamroller is 10% faster than Piledriver on average, and Excavator is 5% on average faster than Steamroller. That means that on average Excavator should be 15.5% faster than Piledriver. That's more or less correct.
If compared to Piledriver (Orochi): Zen has 21.3% - 29.8% higher IPC than
Excavator on average
If compared to Steamroller: Zen has 33.4% - 42.8% higher IPC than
Excavator on average
If AMD hadn't included Orochi to the investor presentation sheet, I would be certain that they are comparing it to Steamroller. Excavator in this context is IMO out of the equation, since it has not been released to desktop (yet) and will never be available in server platforms. Meanwhile the Zeppelin core as well as Orochi core are both intended purely for servers and desktops.
EDIT: The IPC figures are calculated over AMDs own figures (for generational improvement), with 40.1% (left) and 49.9% (right) improvements.
(1) http://i.imgur.com/BQZDIgj.jpg
(2) http://www.slideshare.net/AMD/amd-2...accelerated-processing-units-codenamed-kaveri (page 7)
(3) http://i.imgur.com/BYp4Zz2.png
(4) http://www.amd.com/en-us/who-we-are/corporate-information/events/isscc (page 13)