The CPU frequency is measured at both driver and hardware levels.
The CPU frequency is measured at both driver and hardware levels.
On Linux, tools such as cpufreq-info display CPU frequency at the software level, while programs like i7z access it from the hardware side. It’s true that hardware gives you the raw clock speed, but software provides a more accurate reflection of what your workload actually experiences. Differences in readings often stem from factors like clock modulation and scheduling, which can vary between the two methods.
When reviewing the man page for cpufreq-info, you'll notice it can also fetch data directly from hardware using the -w option. The distinction lies in how it obtains information: software polling reads the /proc/cpuinfo file maintained by the kernel, whereas hardware polling accesses sensors on the CPU itself (often via architecture-specific registers). In many cases, these methods yield similar results. On contemporary CPUs featuring boost and power scaling features, the hardware reading tends to provide the most accurate data.
There are two benefits to using the software method: You don't have to worry about the specific hardware you're working with or any quirks it might have, as the kernel usually has workarounds built in. The drawback is that you're limited by the way the kernel interprets hardware values, whereas direct access would let you control interpretations more freely.