Assembly CPU frequency measuring algorithm

Question

What are the common algorithms being used to measure the processor frequency? JavaScript questions and answers, JavaScript questions pdf, JavaScript question bank, JavaScript questions and answers pdf, mcq on JavaScript pdf, JavaScript questions and solutions, JavaScript mcq Test , Interview JavaScript questions, JavaScript Questions for Interview, JavaScript MCQ (Multiple Choice Questions)

Answer 1

Intel CPUs after Core Duo support two Model-Specific registers called IA32_MPERF and IA32_APERF. MPERF counts at the maximum frequency the CPU supports, while APERF counts at the actual current frequency. The actual frequency is given by: You can read them with this flow ; read MPERF mov ecx, 0xe7 rdmsr mov mperf_var_lo, eax mov mperf_var_hi, edx ; read APERF mov ecx, 0xe8 rdmsr mov aperf_var_lo, eax mov aperf_var_hi, edx but note that rdmsr is a privileged instruction and can run only in ring 0. I don't know if the OS provides an interface to read these, though their main usage is for power management, so it might not provide such an interface.