Software Tuning, Performance Optimization & Platform Monitoring
Discussion regarding monitoring and software tuning methodologies, Performance Monitoring Unit (PMU) of Intel microprocessors, and platform updating.

Measurement of C6 events

Li_T_
Beginner
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Hi,

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.

3. Any other good ways to measure the C6 events?

Thanks in advance.

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