libpfm_intel_skx_unc_pcu — support for Intel Skylake X Power Controller Unit (PCU) uncore PMU


#include <perfmon/pfmlib.h>

PMU name: skx_unc_pcu
PMU desc: Intel Skylake X Server PCU uncore PMU


The library supports the Intel Skylake X Server Power Controller Unit uncore PMU.


The following modifiers are supported on Intel Skylake X server PCU uncore PMU:


Enable edge detection, i.e., count only when there is a state transition from no occurrence of the event to at least one occurrence. This modifier must be combined with a threshold modifier (t) with a value greater or equal to one.  This is a boolean modifier.


Set the threshold value. When set to a non-zero value, the counter counts the number of HA cycles in which the number of occurrences of the event is greater or equal to the threshold.  This is an integer modifier with values in the range [0:15].


Invert the meaning of the threshold or edge filter. If set, the event counts when strictly less than N occurrences occur per cycle if threshold is set to N. When invert is set, then threshold must be set to non-zero value. If set, the event counts when the event transitions from occurring to not occurring (falling edge) when edge detection is set. This is a boolean modifier

Frequency band filtering

There are 3 events which support frequency band filtering, namely, UNC_P_FREQ_BAND0_CYCLES, UNC_P_FREQ_BAND1_CYCLES, UNC_P_FREQ_BAND2_CYCLES, UNC_P_FREQ_BAND3_CYCLES. The frequency filter (available via the ff modifier) is stored into a PMU shared register which hold all 4 possible frequency bands, one per event. However, the library generate the encoding for each event individually because it processes events one at a time. The caller or the underlying kernel interface may have to merge the band filter settings to program the filter register properly.


Stephane Eranian <>


January, 2018 Linux Programmer's Manual