поддержка Intel IceLakeX core PMU (support for Intel IceLakeX core PMU)
Имя (Name)
libpfm_intel_icx - support for Intel IceLakeX core PMU
Синопсис (Synopsis)
#include <perfmon/pfmlib.h>
PMU name: icx
PMU desc: Intel IceLakeX
Описание (Description)
The library supports the Intel IceLakeX core PMU. It should be
noted that this PMU model only covers each core's PMU and not the
socket level PMU.
On IceLake, the number of generic counters depends on the
Hyperthreading (HT) mode.
The pfm_get_pmu_info() function returns the maximum number of
generic counters in num_cntrs.
Модификаторы (Modifiers)
The following modifiers are supported on Intel IceLakeX
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 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].
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
0.
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.
fe_thres
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
[1-4095].
Cобытия отклика вне ядра (Offcore_response events)
Intel IceLakeX supports two encodings for offcore_response
events. In the library, these 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 operating system 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 IceLakeX unlike older processors, the event is treated
as a regular event with a flat set of umasks to choose from. It
is not possible to combine the various requests, supplier, snoop
bits anymore. Therefore the library offers the list of validated
combinations as per Intel's official event list.
