libpfm_intel_skl(3) — Linux manual page


LIBPFM(3)                 Linux Programmer's Manual                LIBPFM(3)

NAME         top

       libpfm_intel_skl - support for Intel SkyLake core PMU

SYNOPSIS         top

       #include <perfmon/pfmlib.h>

       PMU name: skl
       PMU desc: Intel SkyLake

DESCRIPTION         top

       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         top

       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

       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
              [3:65535]. 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.

              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         top

       Intel SkyLake provides two offcore_response events. They are called

       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

       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:




       But the following are illegal:



AUTHORS         top

       Stephane Eranian <>

COLOPHON         top

       This page is part of the perfmon2 (a performance monitoring library)
       project.  Information about the project can be found at 
       ⟨⟩.  If you have a bug report for this
       manual page, send it to  This
       page was obtained from the project's upstream Git repository
       ⟨git:// perfmon2-libpfm4⟩ on
       2020-09-18.  (At that time, the date of the most recent commit that
       was found in the repository was 2020-08-25.)  If you discover any
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                                August, 2015                       LIBPFM(3)