Dell performance profiles and Linux

A few weeks ago we discovered that the performance of our Windows 2012 guest on KVM hypervisors was very bad and it was caused by the "Performance per Watt (DAPC)" profile in the BIOS of our Dell m620 servers. After that, I got curious and started to test with other systems: Linux guests and bare metal. According to the Dell BIOS Performance and Power Tuning documentation, the difference between the performance per watt (dapc) and performance per watt (os) profile should be only a few percent: