AMD Ryzen is the new kid on the block and with every new thing that comes out, there will be something that goes wrong. Besides all the hate towards AMD for bringing innovation into this field, it seems that the Window 10 scheduler does not play well with the new CPUs either.
The new AMD Ryzen chips feature simultaneous multi-threading technology; this technology enables each core to execute two threads at the same time. Intel’s hyper-threading technology also works similarly.
It seems that the Windows 10 scheduler cannot differentiate between principal core threads and virtual SMT threads when it comes to AMD Ryzen and this is causing some performance decrease.
While the AMD Ryzen 7 CPUs have 8 cores and 16 threads, Windows 10 Scheduler interprets it as 16 cores with equal resources for each core. This means that there will be tasks that will be scheduled to a virtual SMT thread instead of a principal core thread.
How Windows 10 Scheduler Sees AMD Ryzen
The following is how Windows 10 Scheduler sees AMD Ryzen:
Windows 10 Scheduler Single Core Thread Mapping:
*————— Data Cache 0, Level 1, 32 KB, Assoc 8, LineSize 64
*————— Instruction Cache 0, Level 1, 64 KB, Assoc 4, LineSize 64
*————— Unified Cache 0, Level 2, 512 KB, Assoc 8, LineSize 64
*————— Unified Cache 1, Level 3, 16 MB, Assoc 16, LineSize 64
-*————– Data Cache 1, Level 1, 32 KB, Assoc 8, LineSize 64
-*————– Instruction Cache 1, Level 1, 64 KB, Assoc 4, LineSize 64
-*————– Unified Cache 2, Level 2, 512 KB, Assoc 8, LineSize 64
-*————– Unified Cache 3, Level 3, 16 MB, Assoc 16, LineSize 64
AMD has been informed of this issue and the company is looking into a fix. AMD has a few words with Microsoft about this issue and it will be interesting to see how quickly this issue will be fixed.
It is safe to say that this is not a very concerning issue and that we have seen this before with Intel hyperthreading.
Let us know what you think about this issue between the AMD Ryzen CPU and Windows 10 Scheduler. Also, let us know whether or not you are being affected by this issue.