libpfm_intel_hsw(3) — Linux manual page


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

NAME         top

       libpfm_intel_hsw - support for Intel Haswell core PMU

SYNOPSIS         top

       #include <perfmon/pfmlib.h>

       PMU name: hsw
       PMU desc: Intel Haswell
       PMU name: hsw_ep
       PMU desc: Intel Haswell-EP

DESCRIPTION         top

       The library supports the Intel Haswell and Haswell-EP core PMU.
       It should be noted that this PMU model only covers each core's
       PMU and not the socket level PMU.

       On Haswell, the number of generic counters depends on the
       Hyperthreading (HT) mode.  When HT is on, then only 4 generic
       counters are available. When HT is off, then 8 generic 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 Haswell

       u      Measure at user level which includes privilege levels 1,
              2, 3. This corresponds to PFM_PLM3.  This is a boolean

       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

       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.

OFFCORE_RESPONSE events         top

       Intel Haswell provides two offcore_response events. They are

       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 Haswell, 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
       2023-06-23.  (At that time, the date of the most recent commit
       that was found in the repository was 2023-06-07.)  If you
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                               April, 2013                     LIBPFM(3)