libpfm_intel_bdw(3) — Linux manual page

NAME \| SYNOPSIS \| DESCRIPTION \| MODIFIERS \| OFFCORE_RESPONSE events \| AUTHORS \| COLOPHON

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

NAME top

       libpfm_intel_bdw - support for Intel Broadwell core PMU

SYNOPSIS top

       #include <perfmon/pfmlib.h>

       PMU name: bdw
       PMU desc: Intel Broadwell

DESCRIPTION top

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

       On Broadwell, 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 Broadwell
       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.

OFFCORE_RESPONSE events top

       Intel Broadwell 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 Broadwell, 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

AUTHORS top

       Stephane Eranian <eranian@gmail.com>

COLOPHON top

       This page is part of the perfmon2 (a performance monitoring
       library) project.  Information about the project can be found at
       ⟨http://perfmon2.sourceforge.net/⟩.  If you have a bug report for
       this manual page, send it to
       perfmon2-devel@lists.sourceforge.net.  This page was obtained
       from the project's upstream Git repository
       ⟨git://git.code.sf.net/p/perfmon2/libpfm4 perfmon2-libpfm4⟩ on
       2024-06-14.  (At that time, the date of the most recent commit
       that was found in the repository was 2024-04-24.)  If you
       discover any rendering problems in this HTML version of the page,
       or you believe there is a better or more up-to-date source for
       the page, or you have corrections or improvements to the
       information in this COLOPHON (which is not part of the original
       manual page), send a mail to man-pages@man7.org

                              October, 2014                    LIBPFM(3)