Windows 10 scheduler does not hurt Ryzen gaming performance (updated)

Posted on Sunday, Mar 12 2017 @ 22:30 CET by Thomas De Maesschalck
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A couple of days ago a popular rumor about AMD's Ryzen CPU gave enthusiasts hope that a patch for the Windows 10 scheduler could result in a big improvement in the chip's gaming performance. It seemed strange that something as simple as that could be the culprit for the lackluster 1080p HD gaming performance seen on the Ryzen platform and now a new article from PC Perspective confirms there's nothing to see here.

The site shows in detail that Windows 10 is correctly enumerating the core structure of Ryzen and debunks rumors about scheduling conflicts. Furthermore, they also heard from multiple high-knowledge AMD insiders that the company does not believe Windows 10's scheduler is hurting performance:
What began as a simple internal discussion about the validity of claims that Windows 10 scheduling might be to blame for some of Ryzen's performance oddities, and that an update from Microsoft and AMD might magically save us all, has turned into a full day with many people chipping in to help put together a great story. The team at PC Perspective believes strongly that the Windows 10 scheduler is not improperly assigning workloads to Ryzen processors because of a lack of architecture knowledge on the structure of the CPU.

In fact, though we are waiting for official comments we can attribute from AMD on the matter, I have been told from high knowledge individuals inside the company that even AMD does not believe the Windows 10 scheduler has anything at all to do with the problems they are investigating on gaming performance.
The testing did reveal that the poor gaming performance may not be a bug but a result of the Ryzen architecture's subdivision into Core Complexes (CCX). PC Perspective discovered there's a lot of latency when workloads end up crossing between CCX modules. This explains why tests like Cinebench do so well why gaming is a whole different story. Cinebench workloads are segmented in small chunks across multiple threads, while games share a lot of actively changing data so these sort of workloads are heavily impacted by the CCX latency:
We do not yet know the exact impact this could have on any specific game, but we do know that communicating across Ryzen cores on different CCX modules takes twice as long as Intel's inter-core communication as seen in the examples above, and 2x the latency of anything is bound to have an impact.
At the moment that's all we have, there's no official statement from AMD.


About the Author

Thomas De Maesschalck

Thomas has been messing with computer since early childhood and firmly believes the Internet is the best thing since sliced bread. Enjoys playing with new tech, is fascinated by science, and passionate about financial markets. When not behind a computer, he can be found with running shoes on or lifting heavy weights in the weight room.



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