The library supports the Intel Westmere core PMU. It should be
noted that this PMU model only covers the each core's PMU and not
the socket level PMU. It is provided separately. Support is
provided for the Intel Core i7 and Core i5 processors (models 37,
The following modifiers are supported on Intel Westmere
u Measure at user level which includes privilege levels 1,
2, 3. This corresponds to PFM_PLM3. This is a boolean
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_INST_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).
The library is able to encode the OFFCORE_RESPONSE_0 and
OFFCORE_RESPONSE_1 events. Those are special events because
they, each, need a second MSR (0x1a6 and 0x1a7 respectively) to
be programmed for the event to count properly. Thus two values
are necessary for each event. The first value can be programmed
on any of the generic counters. The second value goes into the
dedicated MSR (0x1a6 or 0x1a7).
The OFFCORE_RESPONSE events are exposed as normal events with
several umasks which are divided in two groups: request and
response. The user must provide at least one umask from each
group. For instance, OFFCORE_RESPONSE_0:ANY_DATA:LOCAL_DRAM.
When using pfm_get_event_encoding(), two 64-bit values are
returned. The first value corresponds to what needs to be
programmed into any of the generic counters. The second value
must be programmed into the corresponding dedicated MSR (0x1a6 or
When using an OS-specific encoding routine, the way the event is
encoded is OS specific. Refer to the corresponding man page for
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
firstname.lastname@example.org. This page was obtained
from the project's upstream Git repository
⟨git://git.code.sf.net/p/perfmon2/libpfm4 perfmon2-libpfm4⟩ on
2021-04-01. (At that time, the date of the most recent commit
that was found in the repository was 2021-03-23.) If you
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September, 2009 LIBPFM(3)