After ordering a Core i5 7600K Kaby Lake CPU last week, I've been spending the past few days trying it out under Ubuntu Linux. If you happened to pick up an early Kaby Lake CPU and seeing low performance, I wanted to pass along a little PSA while I am still working on additional tests.
After assembling this Core i5 7600K + ASUS PRIME Z270-P + 2 x 8GB DDR4-2400MHz system, I was surprised by the low performance... Here are a few numbers compared to 26 of the other systems in our benchmarking setup.
Out-of-the-box with the Linux 4.10 Git kernel on Ubuntu 16.10 x86_64 with their mainline PPA kernel, the Core i5 7600K performance is rather disappointing.... It's slower than a Core i5 6600K Skylake CPU.
The Skylake i5-6600K is quad-core with 3.5GHz base and 3.9GHz turbo. The Kabylake i5-7600K is quad-core with 3.8GHz base and 4.2GHz turbo while the rest of the specs aren't far off from Skylake.
When seeing those results, one kernel item immediately came to mind as the possible blame: Intel's P-State CPU frequency scaling driver.