Community
cancel
Showing results for 
Search instead for 
Did you mean: 
TAcco1
Beginner
1,562 Views

Skylake-X AVX-512 Throughput

There are conflicting reports regarding AVX-512 ability/throughput on the new Skylake-X processors. It is being reported that all non i9 Skylake-X processors only have half the AVX-512 "FMA units" of the i9 variants. However, several benchmarks are showing AVX-512 performance is comparable on the i7-7800X and i9-7900X, (links: http://forum.hwbot.org/showthread.php?t=170550&page=2 http://forum.hwbot.org/showthread.php?t=170550&page=2 and http://www.pcgameshardware.de/Skylake-X-Codename-266252/News/Core-i7-7800X-AVX512-Durchsatz-1232713/ http://www.pcgameshardware.de/Skylake-X-Codename-266252/News/Core-i7-7800X-AVX512-Durchsatz-1232713/ )

Is it possible to comment on this discrepancy? If not, is there documentation on the Skylake-X processors which would resolve this?

Thanks in advance!

0 Kudos
8 Replies
idata
Community Manager
143 Views

avxthrowaway: Thank you very much for joining the Intel® Processors communities.

 

 

In order to provide the most accurate response I will do further on this matter. As soon as I gather the information needed I will post all the details on this thread.

 

 

Any further questions, please let me know.

 

 

Regards,

 

Alberto R

 

AYee1
Novice
143 Views

If the Core i7 Skylake X models do in fact have the full AVX512 throughput, I'm curious to know how all the pre-release reviews got it wrong. Where did they get their information from?

If you look at the detailed Skylake Server product pages, you can see that it is clearly marked whether they have 1 or 2 x FMA units: ("# of AVX-512 FMA Units")

But if you look at the product pages for the Skylake X parts, the "# of AVX-512 FMA Units" spec is missing.

I don't know whether it was intentionally left out or whether it was just an oversight.

TAcco1
Beginner
143 Views

I am still waiting for a comment on the original question. Can you please provide a link to the second datasheet for the Skylake-X processors? The first one is here for reference

https://www.intel.com/content/www/us/en/products/processors/core/6th-gen-x-series-datasheet-vol-1.ht... 6th Gen Intel® Core™ X-Series Processor Family Datasheet, Vol. 1

I'm assuming since this product is released, you have the second datasheet and haven't updated your links to it?

I look forward to your response.

TAcco1
Beginner
143 Views

Does the i7-7800X have 2 AVX-512 FMA units? (1 full and 1 fused).

Please link the second data sheet for the Skylake-X processors.

Ronny_G_Intel
Moderator
143 Views

Hi avxthrowaway:

We support up to 2 AVX 512 FMA units on SKL-X SKUs.

VX FMA information is considered sensitive. That is the reason it was removed from the datasheets.

I hope this helps,

Ronny G

Jeffrey_H_Intel
Employee
143 Views

Why is AVX FMA count sensitive? Core-X series is a shipping product. We need to document the features of the product for customers.

idata
Community Manager
143 Views

JeffHammond, let me check and see if I can find more information regarding this matter,

Regards,

Amy C.

idata
Community Manager
143 Views

/thread/116484 JeffHammond, thank you for your patience.

We have included the AVX count information on https://ark.intel.com/ Intel® Product Specifications

https://ark.intel.com/products/126695/Intel-Core-i9-7940X-X-series-Processor-19_25M-Cache-up-to-4_30...

Regards,

Amy C.

Reply