Hi Greco Alessia,
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Overriding Dynamic CPU Frequency Detection in Windows 11 ARM Virtual Machines via QEMU Table Injection
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Greco Alessia
40
Reputation points
Hello! We are optimizing Windows 11 ARM guest performance within a QEMU-emulated infrastructure to ensure consistent benchmarking results. We notice irregular, fluctuating clock speed readings across individual vCPUs and require a method to force the guest operating system to recognize a static, uniform frequency value. Despite manual injections of specified LowestFrequency and NominalFrequency parameters into the ACPI CPPC (Type 12) structures, as well as modifications to the SMBIOS Type 4 Max Speed and Current Speed fields, the Windows kernel continues to ignore these static definitions. How can we manipulate the hypervisor's firmware presentation so that Windows 11 adheres to these hardcoded frequency metrics rather than dynamically polling the varying host physical processor states? Thanks in advance.
Windows for business | Windows Client for IT Pros | Devices and deployment | Set up upgrades and drivers
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VPHAN 42,485 Reputation points Independent Advisor2026-05-15T09:11:17.9466667+00:00 -
VPHAN 42,485 Reputation points Independent Advisor
2026-05-13T14:42:22.0033333+00:00 Hi Greco Alessia,
The technically correct and supported approach in a QEMU ARM benchmarking environment is to stabilize the virtualization layer. This includes keeping a fixed virtual CPU topology, pinning QEMU vCPU and IOThread execution to dedicated host cores, minimizing host scheduler interference, and configuring the Windows guest for maximum performance using documented
powercfgprocessor settings such asPROCTHROTTLEMIN 100andPROCTHROTTLEMAX 100. These policies are associated with the active power scheme stored underHKLM\SYSTEM\CurrentControlSet\Control\Power\User\PowerSchemes, but they influence processor policy behavior rather than overriding runtime telemetry.There is currently no supported Microsoft mechanism that forces Windows 11 ARM to permanently trust static SMBIOS or ACPI CPPC frequency declarations over live processor performance feedback in a virtualized environment. Remaining clock variability after host-side stabilization is typically caused by hypervisor scheduling behavior, thermal management, or runtime power-management heuristics rather than missing firmware fields.
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