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

NAME         top

       libpfm_intel_snbep_unc_cbo  - support for Intel Sandy Bridge-EP C-Box
       uncore PMU

SYNOPSIS         top

       #include <perfmon/pfmlib.h>

       PMU name: snbep_unc_cbo[0-7]
       PMU desc: Intel Sandy Bridge-EP C-Box uncore PMU

DESCRIPTION         top

       The library supports the Intel Sandy Bridge C-Box (coherency engine)
       uncore PMU.  This PMU model only exists on Sandy Bridge model 45.
       There is one C-box PMU per physical core. Therefore there are eight
       identical C-Box PMU instances numbered frmo 0 to 7. On dual-socket
       systems, the number refers to the C-Box PMU on the socket where the
       program runs. For instance, if running on CPU8, then snbep_unc_cbo0
       refers to the C-Box for physical core 0 on socket 1. Conversely, if
       running on CPU0, then the same snbep_unc_cbo0 refers to the C-Box for
       physical core 0 but on socket 0.

       Each C-Box PMU implements 4 generic counters and a filter register
       used only with certain events and umasks.

MODIFIERS         top

       The following modifiers are supported on Intel Sandy Bridge C-Box
       uncore PMU:

       i      Invert the meaning of the event. The counter will now count C-
              Box 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 threshold
              modifier (t) with a value greater or equal to one.  This is a
              boolean modifier.

       t      Set the threshold value. When set to a non-zero value, the
              counter counts the number of C-Box 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].

       nf     Node filter. Certain events, such as UNC_C_LLC_LOOKUP,
              UNC_C_LLC_VICTIMS, provide a NID umask.  Sometimes the NID is
              combined with other filtering capabilities, such as opcodes.
              The node filter is an 8-bit max bitmask. A node corresponds to
              a processor socket. The legal values therefore depend on the
              underlying hardware configuration. For dual-socket systems,
              the bitmask has two valid bits [0:1].

       cf     Core Filter. This is a 3-bit filter which is used to filter
              based on physical core origin of the C-Box request. Possible
              values are 0-7. If the filter is not specified, then no
              filtering takes place.

       tf     Thread Filter. This is a 1-bit filter which is used to filter
              C-Box requests based on logical processor (hyper-thread)
              identification. Possibles values are 0-1. If the filter is not
              specified, then no filtering takes place.

Opcode filtering         top

       Certain events, such as UNC_C_TOR_INSERTS supports opcode matching on
       the C-BOX transaction type. To use this feature, first an opcode
       matching umask must be selected, e.g., MISS_OPCODE.  Second, the
       opcode to match on must be selected via a second umask among the
       OPC_* umasks.  For instance, UNC_C_TOR_INSERTS:OPCODE:OPC_RFO, counts
       the number of TOR insertions for RFO transactions.

       Opcode matching may be combined with node filtering with certain
       umasks. In general the filtering support is encoded into the umask
       name, e.g., NID_OPCODE supports both node and opcode filtering. For
       instance, UNC_C_TOR_INSERTS:NID_OPCODE:OPC_RFO:nf=1.

AUTHORS         top

       Stephane Eranian <>

COLOPHON         top

       This page is part of the perfmon2 (a performance monitoring library)
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                                August, 2012                       LIBPFM(3)