During the Ryzen launch, some interesting performance problems popped up for Windows 10. Due to the way Windows 10 handled power states for Ryzen, performance was markedly different compared to Windows 7. In order to resolve the issue, users had to choose the High performance power plan instead of the usual Balanced power plan. After committing to the issue after launch, AMD has released a patch that resolves the issue.
According to AMD, the issue is with the core parking in Windows 10. For Windows 7, all physical cores are kept active and logical cores are turned off. In Windows 10, a single physical core and a single logical core is kept active, reducing performance as it takes longer for cores to spin up when required. With the new patch, Ryzen processors will move to the Windows 7 style core parking, which according to AMD, Intel does for their processors in Windows 10 as well. In fact, the improved performance when utilizing Intel’s chipset drivers compared to the generic Windows ones may be due to this issue.
The other issue getting fixed is with P-state transitions. For the default, generic Windows 10 Balanced plan, the transitions between different P-states has thresholds that are too high. With the patch, AMD has modified timers and thresholds for P-state transitions to better integrate with SenseMI and allow for better hardware control. Interestingly AMD is claiming that there will be no increases in power consumption as C states will still be entered into for the “active” cores.
In order to enable the new power profile, you just simply need to install the patch file AMD has provided. Moving forward, the new power profile will be enabled by default as part of AMD’s Chipset drivers. Combining much of the performance of High performance and the power savings of Balanced, it looks like AMD has hit the sweet spot for Ryzen. I expect we will get further refinements for the power profile as AMD continues to work on integrating Ryzen into Windows 10.
