ACPI CPUfreq vs. Intel P-State Scaling With Linux 3.15

When running simply the PostMark disk benchmark, there was only one outlier and that was the Intel P-State driver with the performance governor that was actually slower than P-State with the powersave governor or ACPU CPUfreq with all tested scaling governors. The default configuration of the tested Ubuntu 3.15 Linux Git vanilla kernel was in the slowest state for PostMark.

The Intel P-State driver in the performance mode was slower for PostMark, but during the testing process it consistently consumed about 10 Watts (or about 5%) less than the other CPU scaling modes.

When figuring out the performance-per-Watt, the performance between all five tested configurations ended up being close to the same.

For our first Linux graphics test was running Unigine Tropics with the discrete AMD Radeon graphics card using the R600 Gallium3D driver. When it comes to the raw performance, all five configurations ended up having the same FPS value.

While the frame-rates were the same, the overall system power consumption in each configuration varied... ACPI cpufreq with the performance governor was consuming the most amount of power on average while the Intel P-State driver with the powersave governor was consuming the least amount of power.

When calculating the performance-per-Watt based upon this data, the Intel P-State driver with the powersave governor was delivering the best results from this Core i7 4960X EE system with Radeon graphics.