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NAME | SYNOPSIS | DESCRIPTION | MODIFIERS | Opcode filtering | AUTHORS | COLOPHON |
LIBPFM(3) Linux Programmer's Manual LIBPFM(3)
libpfm_intel_snbep_unc_cbo - support for Intel Sandy Bridge-EP C-Box
uncore PMU
#include <perfmon/pfmlib.h>
PMU name: snbep_unc_cbo[0-7]
PMU desc: Intel Sandy Bridge-EP C-Box uncore PMU
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.
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.
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.
Stephane Eranian <eranian@gmail.com>
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 2017-07-05. If you dis‐
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COLOPHON (which is not part of the original manual page), send a mail
to man-pages@man7.org
August, 2012 LIBPFM(3)