libpfm_intel_snbep_unc_cbo(3) — Linux manual page

NAME \| SYNOPSIS \| DESCRIPTION \| MODIFIERS \| Opcode filtering \| AUTHORS \| COLOPHON

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 <[email protected]>

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 [email protected].
       This page was obtained from the project's upstream Git repository
       ⟨git://git.code.sf.net/p/perfmon2/libpfm4 perfmon2-libpfm4⟩ on
       2025-08-11.  (At that time, the date of the most recent commit
       that was found in the repository was 2025-06-29.)  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 [email protected]

                               August, 2012                     LIBPFM(3)