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, 44).
The following modifiers are supported on Intel Westmere processors:
u Measure at user level which includes privilege levels 1, 2, 3.
This corresponds to PFM_PLM3. This is a boolean modifier.
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
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
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,
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 0x1a7).
When using an OS-specific encoding routine, the way the event is
encoded is OS specific. Refer to the corresponding man page for more
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@example.com. This
page was obtained from the project's upstream Git repository
⟨git://git.code.sf.net/p/perfmon2/libpfm4⟩ on 2017-03-13. If you dis‐
cover 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
September, 2009 LIBPFM(3)