AMD Confirms Windows 10 Thread Scheduler Working Fine for Ryzen

/ 1 week ago

AMD Ryzen

After the launch of Ryzen, there was speculation about the impact of OS optimisation for performance on AMD’s new Zen architecture. One issue that has been bouncing around the community is with the Windows 10 Thread Scheduler not properly assigning tasks to the two CCX units and the between the physical and logical cores. In a statement that is sure to shock, AMD has investigated the issue and things are apparently a-okay.

The reports first gained ground when users saw a discrepancy between Windows 7 and Windows 10 performance, with Ryzen surprisingly performing better than expected with the old OS. According to AMD, this has nothing to do with the thread scheduler but more to due to Microsoft’s changes in software system architecture. This might be simply due to how the OS handles system resource allocation and not due to the thread scheduler.

There were two main reasons as to why the Windows 10 Thread Scheduler was blamed. One was that the scheduler was not aware of the CCX architecture and was improperly load balancing, either balancing the load on one of the 2 CCX lopsidedly or conversely, increasing the inter-CCX communication unnecessarily. The other reason was that Windows 10 was not properly distinguishing between the logical and physical cores when assigning work. It appears that AMD’s implementation of SMT is similar enough to Intel’s HyperThreading that an OS patch will not be required.

With this confirmation that the thread scheduler is not at issue, it means there won’t be any one quick fix for improving Ryzen and Zen performance. With Bulldozer, a relatively simple patch fixed the CMT implementation but this time, it will take more work. Instead of turning to a simple OS fix, it looks like the programs being run themselves will need to be optimized for the new architecture, a process that may take months if not years. Hopefully, software developers get on board quickly so we can eke even more performance out of Zen and fully utilise the new architecture.

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