NAME | SYNOPSIS | DESCRIPTION | MODIFIERS | OFFCORE_RESPONSE events | SEE ALSO | AUTHORS | COLOPHON

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

NAME         top

       libpfm_intel_snb - support for Intel Sandy Bridge core PMU

SYNOPSIS         top

       #include <perfmon/pfmlib.h>

       PMU name: snb
       PMU desc: Intel Sandy Bridge
       PMU name: snb_ep
       PMU desc: Intel Sandy Bridge EP

DESCRIPTION         top

       The library supports the Intel Sandy Bridge core PMU. It should be
       noted that this PMU model only covers each core's PMU and not the
       socket level PMU. For that refer to the Sandy Bridge uncore PMU
       support.

       On Sandy Bridge, 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 Sandy Bridge
       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:LATENCY_ABOVE_THRESHOLD 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).

OFFCORE_RESPONSE events         top

       Intel Sandy Bridge provides two offcore_response events, like Intel
       Westmere.  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 Sandy Bridge, 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

SEE ALSO         top

       libpfm_snb_unc(3)

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⟩ on 2017-03-13.  If you dis‐
       cover 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

                                January, 2011                      LIBPFM(3)