bionic (3) libpfm_intel_snb.3.gz

NAME

       libpfm_intel_snb - support for Intel Sandy Bridge core PMU

SYNOPSIS

       #include <perfmon/pfmlib.h>

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

DESCRIPTION

       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

       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

       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

       libpfm_snb_unc(3)

AUTHORS

       Stephane Eranian <eranian@gmail.com>

                                                  January, 2011                                        LIBPFM(3)