I am trying to measure the C6 events (enters and leaves C6) for each core. I am using i7-5820K (haswellEP) and just found the C6 residency (% of time on C6) performance counters. The only performance counters I found might be useful is "DEMOTIONS_CORE0" to "DEMOTIONS_CORE17". So my questions are
1. Is the performance counter "DEMOTIONS_CORE0" related to the numbers of C6 exits? And why there are 18 "DEMOTIONS_CORE" performance counters since i7-5820K only has 6 cores.
2. It seems using ACPI might be easier to get the numbers of C6 events. How these ACPI based numbers are different from the performance counter based numbers.