NAME¶
libpfm_intel_snbep_unc_cbo - support for Intel Sandy Bridge-EP C-Box uncore PMU
SYNOPSIS¶
#include <perfmon/pfmlib.h>
PMU name: snbep_unc_cbo[0-7]
PMU desc: Intel Sandy Bridge-EP C-Box uncore PMU
DESCRIPTION¶
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¶
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¶
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¶
Stephane Eranian <eranian@gmail.com>