The library supports the Intel SkyLake core PMU. It should be
noted that this PMU model only covers each core's PMU and not the
socket level PMU.
On SkyLake, the number of generic counters depends on the
Hyperthreading (HT) mode.
counters are available. The pfm_get_pmu_info() function returns
the maximum number of generic counters in num_cntrs.
The following modifiers are supported on Intel SkyLake
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_TRANS_RETIRED:LOAD_LATENCY 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).
intx Monitor the event only when executing inside a
transactional memory region (in tx). Event does not count
otherwise. This is a boolean modifiers. Default value is
intxcp Do not count occurrences of the event when they are inside
an aborted transactional memory region. This is a boolean
modifier. Default value is 0.
This modifier is for the FRONTEND_RETIRED event only. It
defines the period in core cycles after which the
IDQ_*_BUBBLES umask counts. It acts as a threshold, i.e.,
at least a period of N core cycles where the frontend did
not deliver X uops. It can only be used with the
IDQ_*_BUBBLES umasks. If not specified, the default
threshold value is 1 cycle. the valid values are in
Intel SkyLake provides two offcore_response events. They are
called OFFCORE_RESPONSE_0 and OFFCORE_RESPONSE_1.
Those events need special treatment in the performance monitoring
infrastructure because each event uses an extra register to store
some settings. Thus, in case multiple offcore_response events are
monitored simultaneously, the kernel needs to manage the sharing
of that extra register.
The offcore_response events are exposed as a normal events by the
library. The extra settings are exposed as regular umasks. The
library takes care of encoding the events according to the
underlying kernel interface.
On Intel SkyLake, the umasks are divided into three categories:
request, supplier and snoop. The user must provide at least one
umask for each category. The categories are shown in the umask
There is also the special response umask called ANY_RESPONSE.
When this umask is used then it overrides any supplier and snoop
umasks. In other words, users can specify either ANY_RESPONSE OR
any combinations of supplier + snoops.
In case no supplier or snoop is specified, the library defaults
to using ANY_RESPONSE.
For instance, the following are valid event selections:
But the following are illegal:
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 perfmon2-libpfm4⟩ on
2021-08-27. (At that time, the date of the most recent commit
that was found in the repository was 2021-08-04.) 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 firstname.lastname@example.org
August, 2015 LIBPFM(3)