# libpfm_intel_skl

## NAME



           libpfm_intel_skl - support for Intel SkyLake core PMU
    


## SYNOPSIS



           **#include <perfmon/pfmlib.h>**
    
           **PMU name: skl**
           **PMU desc: Intel SkyLake**
    


## DESCRIPTION



           The library supports the Intel SkyLake core PMU. It should be
           noted that this PMU model only covers each core's PMU and not the
           socket level PMU.
    
           On SkyLake, the number of generic counters depends on the
           Hyperthreading (HT) mode.
    
           counters are available. The **pfm_get_pmu_info()** function returns
           the maximum number of generic counters in **num_cntrs.**
    


## MODIFIERS



           The following modifiers are supported on Intel SkyLake processors:
    
           **u** Measure at user level which includes privilege levels 1, 2,
                  3. This corresponds to **PFM_PLM3**.  This is a boolean
                  modifier.
    
           **k** Measure at kernel level which includes privilege level 0.
                  This corresponds to **PFM_PLM0**.  This is a boolean modifier.
    
           **i** Invert the meaning of the event. The counter will now count
                  cycles in which the event is **not** occurring. This is a
                  boolean modifier
    
           **e** 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
                  counter mask modifier (m) with a value greater or equal to
                  one.  This is a boolean modifier.
    
           **c** Set the counter mask value. The mask acts as a threshold.
                  The counter will count the number of 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 [0:255].
    
           **t** Measure on both threads at the same time assuming hyper-
                  threading is enabled. This is a boolean modifier.
    
           **ldlat** Pass a latency threshold to the
                  MEM_TRANS_RETIRED:LOAD_LATENCY event.  This is an integer
                  attribute that must be in the range [1:65535]. It is
                  required for this event.  Note that the event must be used
                  with precise sampling (PEBS).
    
           **intx** Monitor the event only when executing inside a
                  transactional memory region (in tx). Event does not count
                  otherwise. This is a boolean modifiers. Default value is 0.
    
           **intxcp** Do not count occurrences of the event when they are inside
                  an aborted transactional memory region. This is a boolean
                  modifier. Default value is 0.
    
           **fe_thres**
                  This modifier is for the FRONTEND_RETIRED event only. It
                  defines the period in core cycles after which the
                  IDQ_*_BUBBLES umask counts. It acts as a threshold, i.e.,
                  at least a period of N core cycles where the frontend did
                  not deliver X uops. It can only be used with the
                  IDQ_*_BUBBLES umasks. If not specified, the default
                  threshold value is 1 cycle. the valid values are in
                  [1-4095].
    


## OFFCORE_RESPONSE events



           Intel SkyLake provides two offcore_response events. They are
           called OFFCORE_RESPONSE_0 and OFFCORE_RESPONSE_1.
    
           Those events need special treatment in the performance monitoring
           infrastructure because each event uses an extra register to store
           some settings. Thus, in case multiple offcore_response events are
           monitored simultaneously, the kernel needs to manage the sharing
           of that extra register.
    
           The offcore_response events are exposed as a normal events by the
           library. The extra settings are exposed as regular umasks. The
           library takes care of encoding the events according to the
           underlying kernel interface.
    
           On Intel SkyLake, the umasks are divided into three categories:
           request, supplier and snoop. The user must provide at least one
           umask for each category. The categories are shown in the umask
           descriptions.
    
           There is also the special response umask called **ANY_RESPONSE**. When
           this umask is used then it overrides any supplier and snoop
           umasks. In other words, users can specify either **ANY_RESPONSE OR**
           any combinations of supplier + snoops.
    
           In case no supplier or snoop is specified, the library defaults to
           using **ANY_RESPONSE**.
    
           For instance, the following are valid event selections:
    
           **OFFCORE_RESPONSE_0:DMND_DATA_RD:ANY_RESPONSE**
    
           **OFFCORE_RESPONSE_0:ANY_REQUEST**
    
           **OFFCORE_RESPONSE_0:ANY_RFO:LLC_HITM:SNOOP_ANY**
    
           But the following are illegal:
    
           **OFFCORE_RESPONSE_0:ANY_RFO:LLC_HITM:ANY_RESPONSE**
    
           **OFFCORE_RESPONSE_0:ANY_RFO:LLC_HITM:SNOOP_ANY:ANY_RESPONSE**
    


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