AMD says there’s no Windows 10 scheduling bug affecting Ryzen’s performance

Madeleine Dean By: Madeleine Dean
2 minute read

Home » News » AMD says there’s no Windows 10 scheduling bug affecting Ryzen’s performance

Many AMD Ryzen users have reported that the processor’s performance is lower than it could be on Windows 10. Ryzen is still much faster than any previous AMD CPU, but somehow its performance is not optimal when running certain tasks.

Many users suggested the culprit for this performance issue as Windows 10’s scheduler and how it isn’t able to correctly identify Ryzen’s principal core threads from virtual SMT threads. As a result, Windows 10 doesn’t assign the tasks to a principal core thread. Instead, it schedules many of them to a virtual SMT thread.

In fact, Microsoft even officially acknowledged this issue and confirmed a fix in the works — despite AMD saying that there is no Windows 10 thread scheduler issue affecting Ryzen’s performance.

AMD says Windows 10 doesn’t have a Ryzen scheduling bug

Here’s what the company said in an official blog post:

We have investigated reports alleging incorrect thread scheduling on the AMD Ryzen™ processor. Based on our findings, AMD believes that the Windows 10 thread scheduler is operating properly for “Zen,” and we do not presently believe there is an issue with the scheduler adversely utilizing the logical and physical configurations of the architecture.

As an extension of this investigation, we have also reviewed topology logs generated by the Sysinternals Coreinfo utility. We have determined that an outdated version of the application was responsible for originating the incorrect topology data that has been widely reported in the media. Coreinfo v3.31 (or later) will produce the correct results.

Finally, we have reviewed the limited available evidence concerning performance deltas between Windows 7 and Windows 10 on the AMD Ryzen CPU. We do not believe there is an issue with scheduling differences between the two versions of Windows.  Any differences in performance can be more likely attributed to software architecture differences between these OSes.

Going forward, our analysis highlights that there are many applications that already make good use of the cores and threads in Ryzen, and there are other applications that can better utilize the topology and capabilities of our new CPU with some targeted optimizations. These opportunities are already being actively worked via the AMD Ryzen™ dev kit program that has sampled 300+ systems worldwide.

As AMD explains, the software/hardware relationship is a complex one, especially when preexisting software is exposed to an all-new CPU architecture.



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