I'm trying to find out the ways in which it is possible to read the current frequency at which the CPU is operating in order to be able to make more sense of the results of RDTSC.
It seems that on Linux the preferred way to read this value is to read from /dev/cpu/CPUID/msr, as the Intel PCM library does. However, where those file are read-protected, I find myself at a dead-end, since the RDMSR instruction must be run at privilege level 0. Is it really the best I can do to grep the Processor Brand String from CPUID.0x80000002-04 for its "GHz" portion (not that I imagine that reflects the current frequency)? Is there any other way to find out the current CPU frequency?