We have done CPUFreq and PState benchmarks many times. However, given how well the R9 285 Tonga is running with AMDGPU PowerPlay as of Linux 4.5, I decided to run some fresh P-State vs. CPUFreq benchmarks on Linux 4.5-rc1.
P-State powersave, P-State performance, CPUFreq ondemand, CPUFreq powersave, and CPUFreq performance were tested on this Radeon R9 285 setup. The only variable being changed between testing was the CPU scaling driver/governor. For those new here, the only reason why the CPU frequency is reported differently on the automated system table is that CPUFreq exposes the CPU clock base frequency while P-State reports the turbo boost frequency via the same sysfs file.
Head on over to this OpenBenchmarking.org result file to see all the results from these Linux OpenGL gaming tests! The results are similar to our past CPU governor/driver comparisons. With viewing the results on OpenBenchmarking.org, don't forget to share your thoughts on the new OpenBenchmarking.org site that's now in beta.